Mini popup toy hauler (using rooftop tent)

[DrewsBrews]

Hi all. This is a continuation of The Snuzie Cube, however that project went south. I am taking the frame I built and going a different direction. I figured it would be best to start fresh with a new thread to be less confusing.

So I have a 5ftx10ft frame with 1400lb of spring rating to work with. I've also got a rooftop tent to mount on it. The tent is a clamshell type: A hard floor that mounts to a sturdy car roof rack. You would normally mount it so the tent opens off to the side of the vehicle. It is a large version 6ftx4ft that opens to 6ftx8ft with an included 2" Cali king size mattress (roughly).

The plan: To build an aproximately 5ft(w) x4ft(d) x2ft(h) box up towards the front of the frame with hatches for storage and possibly an A/C unit. Then, behind that (the rest of the 5ftx6ft area of the frame) will have composite decking to act as a small flatbed for bringing large things that wouldn't fit in a car and be a pain to get up in a truck bed if that is the tow vehicle. The tent will be mounted on top of the storage box up front and open towards the rear. This gives a small 2ft step out to the decking (will replace tent ladder with a smaller 1-2step one). And will have a small step stool to step off the trailer from there. I also have a roof rack mount style awning to mount somehow to the side (with zip on enclosure if needed).

The trailer is 5ft wide, while the tent is 6ft. So the tent will hang over the sides aprox. 6".

The trailer frame is not yet registered. I will be doing so as a "self built". Here in Ohio, utility/cargo type non-commercial trailers under a certain weight are not titled, only registered. However camper trailers are titled (If it encloses a mattress it is considered a camper). That was always an iffy part for me during the previous project. I heard nightmares of trying to get a self built camper titled in Ohio. At that time I was hoping to squeeze through the cracks by registering the frame as utility/cargo and building the rest on top of it.. not unlike what people do for teardrops on Harbor freight frames (though I was not happy with the idea). Fortunately It never got to that point, and this time around it basically will be a utility trailer with a small enclosed cargo area and tongue box. The tent is a seperate item. Makes it alot more cut and dry come inspection time.

 

[DrewsBrews]

I built the storage box frame from 1" angle steel. Supports were added to handle the weight of the tent (and us) on top. The tent itself is 165lb. The frame is probably ~60+lb.

I hosed the frame down with Rustoleum farm equipment paint to prevent the welds from rusting up.

Side hatches will clear properly from outside, I just propped it from behind to get the pic.

I picked up some 1/4" HDPE sheet to clad the box with. Then cut it to closer sizes for their application.

 

[DrewsBrews]

Doin some spitball'n..

I've got a 5000btu window A/C unit. My idea was to mount it inside the box, with a hatch at the back of the box that opens to exhaust into the flatbed area. I was racking my brain trying to figure out how to plumb all the various supply and return air. Through some quick research, I found that for tents often just the cold supply air is pumped in while "return" air is pulled from outside. Certainly not efficient, but the entire situation is about as inefficient as it gets. I hope to only need it to cool off just before bedtime and turn it off sometime into the night as I doubt we would be using the tent much durring the day.

The controls for temp and fan speed are manual knobs/rotary switches. This will probably render the temp control useless as it would not have an easy way to monitor the tent temp. (not saying impossible to do, just not something I feel the need to persue). So it would likely just stay on 100% duty cycle. Also I doubt there will be a need to fiddle with the fan speed.. I'd just find the best speed for the setup and leave it there. So a simple on/off switch could suffice. Though an off/fan/fan+cool select option would be nice.

Things to do If I try this route:
-Fashion some sort of adapter from the cold air outlet to some sewer pipe (something like 6"). Maybe heat-form some kydex to make the adapter. Hoping to avoid fiberglassing, but that is also an option.
-Plumb the sewer pipe up through the top of the box into the tent floor.. probably at the center of the head end. Then a 22 or 45deg elbow could be popped on after the tent is opened.
-Install an air switch in the tent floor (garbage disposal type) to control the unit. Less 110v in the tent.
-Seal the connections between the box and tent. Sofar thinking a house roof boot could do the trick. unless you guys have better ideas?
-Find a way to vent the box for intake air supply to both the hot and cold sides of the unit.

 

[DrewsBrews]

I decided to cut a vent hole for the air intake in the bottom of the box while I am installing the panel. I went on the prowl for something that could offer some protection from those "oah crap I just ran over that at highway speed" moments... and to hold in some bug screen. Home depot offers expanded steel mesh, but it is bare steel and $22 for the smallest piece. Then I found Menards has wire shelf pieces for heavy grade shelving. Aprox. 15"x24" for under $5. The "wire" looks to be near 3/16". Feels very sturdy.

I figured a 12"x20" hole should be plenty for both hot and cold side intake on the A/C. I will save the cutout to use as a cover. The jigsaw blade starter hole was widened out to be a thumb hole for easy removal. Will come up with some sort of retention so it doesn't get blown or bounced out

I then drilled some of the bolt holes so I could hold it down and trim the panel edges flush with the frame. This HDPE is nice to work with. Even my tired old flush trim bit sailed right through the stuff.

After cleaning up and taking a moment to reflect on it. I'm wondering about putting a bevel on the edges of this panel. That would act to reduce water wicking up in the gap and sitting there working to rust the steel. In essence: would make the bottom edges of the vertical panels act more as drip edges. Though it could make trimming those panels more tricky as there is less material for a bit bearing to ride on. I have some mulling to do.

I found the HDPE moves alot as it warms up from the sun. Shaded areas don't expand, while spots in the sun expand to make it crinkle like bacon. And that is just a sheet sitting out by itself with nothing trying to hold it down. I plan to rivet the panels to the frame. I will need to drill larger holes than the rivet shaft so it can move around without putting too much strain on the rivets. I imagine the white HDPE sheet would do better.

 

[DrewsBrews]

Nevermind about the bevel, that is the least of my worries. This stuff expands even more than I thought.. Seems maybe over 1/16" per foot when in full sun in mid 70s temp. I flushed the other end to take this photo. This is how much this 5ft length expands compared to when I flush trimmed it in the shade.

So I opted to center the piece and re-trim it. That way it can't expand and try popping off the side panels. I pulled it into the shade to let it retract then opened up the bolt holes in the plastic and drilled all the rivet holes. I figure shade in the 70s is a good mid point as it will also see freezing temps over winter. Enlarged holes allow expansion and contraction from there.

 

[DrewsBrews]

Continued today with the process of setting panels in the sun to expand, then trimming to size before putting in the shade to retract and drill the rivet holes. Slow process but getting through it.

I trimmed the rear panel and cut the hole for the A/C exhaust hatch. It will be mostly held in with the side rails and a tiedown reinforcement bar for the rear flatbed section. Planning only to rivet the top edge, so I held off on attaching it for the moment.

While waiting for the front panel to heat up I cut and bent some angle iron to make a bracket to hold up the front of the A/C unit. Planning to drill and bolt it in place once the appropriate height is determined.

Then I trimmed and riveted the front panel.

 

[DrewsBrews]

Next days into next week has rain chance creeping in so I pushed a little more than normal today. I attached the back panel so I could prepare and attach the sides. Figured out placement of the shore power hookup. Required a little grinding for clearance to squeeze it in the corner.

Still debating if I will run 120v into the tent on a more permanent basis. I have a 12v power supply that is rated for something like 10amp. I could wire that up to 12v sockets in the tent for phone chargers and such. I may also add some 12v convenience lighting on the trailer. If I realy need 120v temporarily I can always fish an extension cord from the outside.

I have a deep cycle battery, but we don't plan on doing much, if any, boondocking or primitive camping. If we do, we can get by without power. So right now I'm not particularly interested in the added complexity or maintenance.

 

[DrewsBrews]

I went to the hardware store to get more ideas for ducting the A/C. Standard sch40 4" pipe has the most fitting options but it is heavy. I worry about the weight puting strain on connections as the trailer bounces around. Unsure I'd be able to strap it down well enough. Sewer grade pipe is thinner wall and the fittings are noticeably lighter, but fewer fitting options and isn't compatible with sch40 fittings due to the different OD. Then I checked out galvinized steel ducting. Much lighter overall and has more insulation options. I have worked some sheet metal in my time. Like origami but with steel.

I picked up a 5" round to 12" wide thin register box to do some prototyping. They make smaller round duct but 5" was the smallest they have register boxes for. Should flow with much less restriction than the 4" flexi hoses other folks use for their tears... Which I hear sometimes causes freezing up issues.

Below is the opening I am working with. The fan outlet is offset to the right. It spins counter clockwise so it blows up and towards the left. The insulation foam forms an inner duct with a kickout just to the left of center that begins directing the air forward. I figure I can add more baffling to catch the air coming off that kickout, so I don't need to extend the adapter all the way to the far left side.

I think it could function well enough with some more work. Maybe a little modification to the A/C cowl to open it up too.

It looks like there are some grill options out there for 5" round vents: Amazon.com
I like that this one has mesh behind it to prevent things falling in. And it appears to be painted metal, so it shouldn't break if we accidentally lean on it.

 

[DrewsBrews]

I framed out around the rear hatch with 1x2 PVC trim board so I had something to attach a panel to. It also recesses it all a bit because reasons (to be explained later). If you can't tell I'm shooting for no wood in this build. This PVC trim board isn't the stiffest/strongest stuff. But if I use enough fasteners it should add up to a decent hold.

Then cut some of the spare HDPE for a panel insert.

I figured out how high the A/C unit will be and drilled the forward brace for bolts.

Next up is cutting the A/C exhaust opening and framing around it with more PVC 1x2 to hold the back side of the unit. I hoped to get that all done today, but needed to get dinner started. I might do some more later afterwards. We'll see how much more daylight I have.

 

[DrewsBrews]

I was able to mark out the opening for the A/C exhaust this evening. Measuring and marking for this stuff seems to be a big time sink. Should be able to smash it out tomorrow.

Reflecting on this all... I understand this is a strange build. But with my previous issues on this trailer (receiving letter of impending fines) with my local municipality, and reading into the local zoning statutes.. I have lost faith that they would be OK with me storing a camper trailer of any sort on my property. So I adjusted and the current effort is to have something that looks much more utility-oriented instead.

 

[DrewsBrews]

I cut the exhaust hole and screwed down the bottom board to support the back of the A/C. I plan to surround it at the back with more, but I wanted to get an idea if I was in the ballpark first. So I lugged the unit out to the trailer. At first I thought I mismeasured or miscut something, because it wouldn't come close to butting up flush to the back panel. But it turns out the whole case of the A/C is rather tweaked in it's shape. So I had to do some bending of the forward feet brackets to get it to sit in a way that allowed the back to flush up better.

I offset it to the right a bit. The compressor is on the left so that centers the weight more. That and the duct adapter seems like it will point slightly to the left so I'll work with it rather than fighting it.

That is as far I got. Then it started raining so I packed back up.

 

[DrewsBrews]

Finished up the surround to hold in the rear of the A/C unit. Then trimmed down a wire shelf piece to use as a guard. Used 8x screw down type wire ties. They seem to have a solid hold, but will see how long they hold up. The wire/bars are a little too small for wire P-clamps so this was the best I could come up with for now. I suppose it isn't the end of the world to replace them every few years.

Then I moved on to figuring out the retention of the intake hole cover. I kept it pretty basic. Used one of the PVC boards to give a lip that one edge slides under, then added more on the other side with some elevator bolts for captured thread and threaded knobs to hold a block down. I might need to leave a kneeling pad in the box to use when opening/closing it up.

Then finished it up by bolting the guard back in with some bug screen.

Now that I'm thinking it out I should have attached the hold down block to the cover plate to make it one piece to remove. doh. Maybe I still could, but it would have been easier to drill screw holes from underneath. Now that the bug screen is in place I'd have to mark from the top and cross my fingers the marks are accurate enough. Otherwise it all won't line up properly to reinstall.

 

[DrewsBrews]

Still working on odds and ends today. I finished up on the A/C duct adapter. Added some extra baffle pieces to direct the air. Trimmed the cowling to open it up a bit. Then screwed it down and sealed it up with aluminum tape. Certainly not fancy but it gets the job done.

 

[DrewsBrews]

I got an idea of how long the A/C vent will need to be. A 2ft section cut down should be plenty to meet up to a 90 and the cutoff used to extend up into the tent floor.

I measured out the mounting width of the rails on the tent then drilled holes in the box frame. I also drilled out screw holes to mount the rear hatch but realized I'd want to trim the top panel before screwing the hatch down. That hatch is the only one I'm planning to use screws on since it is attaching to an inner frame. The others I plan to rivet on.

Then I started thinking about a power panel. I'm not sure there will be much that needs mounted, but I decided to add something now rather than wishing I did and needing to crawl in the box to install one later.

I haven't looked at some of the parts I got for a while. I think I got an In-line outdoor rated GFCI breaker that I planned to use it's plug as the shore power plug. I then had a breakered outdoor rated power strip to plug into that. That way I've got at least basic GFCI and current protection from parts that are simple to replace. No tools needed.

 

[DrewsBrews]

I dug into my stash of parts I got for the trailer over the years. Looks like I ended up getting a "Woods" brand model 4644, 4 outlet power block with GFCI (Basically a fancy power strip). I was getting mixed signals if this has any sort of current overload protection. Walmart's listing of it directly states "Reset (on)/off power and 15A circuit breaker switch". The packaging, and even the Woods' spec sheet says "Overload protection" seperately from "GFCI Protection". But the power switch only has the I/O markings on the rocker and there is no text showing "Reset" besides the GFCI test/reset buttons.

I opened it up and the power switch appears to be a standard rocker. No extra bulk behind it to make me think there is anything more special about it. And, besides the GFCI module, I see no other part that would be a breaker or fuse. Unless the GFCI module also has some sort of built-in "Overload protection" that is just not specified. That is not a standard feature of GFCI. Much weirdness.

It does say "Indoor use only" so all the fancy switch boot and receptical covers must be for dust, or I guess "splash" resistance. The case is not sealed, typical calmshell. I'll mount it on the power panel to keep it up off any moisture that might accumulate on the floor of the box. The cord-keeper hoops on the sides will be nice to wire tie the cords to, making them less likely to work loose from movement/vibration. But I guess I do still need to figure out some sort of overcurrent breaker. Currently looking into marine breakers since they have more generic mounting and connections compared to the more proprietary commercial/residential stuff.

 

[working on it]

I installed an LG 5012j 5k btu A/C in the rear bulkhead of my 4x8 trailer, years ago. I used a "Speedi-Boot 90 degree register vent boot" on the exhaust side, instead of the ambient (recirculated) intake/cold air ouput side (front of the A/C unit), and vented it to the curbside of the trailer. Here's one of the threads concerning the installation. WindowshakerA/C: drainpipe /pan/problem solved!

I used a flat cookie sheet and aluminum duct tape to attach it to the A/C, and it remains working fine, 12 years later.

Since you're going in the opposite direction than I did, I only have a couple or three suggestions for you. The small diameter cold air output duct could use some help: use some fiberglass/mylar insulation on the outside, to keep more cold air from losing temp to the ambient air, and, if you'd install an axial fan inside the duct, it might increase the airflow velocity. (I did both on the exhaust side, and it helped a lot). Also, I added a computer case fan to help cool the A/C's coils, since the unit is inside an enclosed trailer (the unit can be operated with the rear hatch closed and locked at night).

Another thing: the A/C (with its' own type of GFCI in the cord), and the accessory fans, are plugged into another GFCI inside the cabin, so I know that if any part fails or overheats, all will shut down at the same time. Safety whilst asleep!

 

[DrewsBrews]

@working on it
Heck yeah! I used large aluminum baking sheets to make a fan shroud for electric fan conversion on a truck years ago.

Typically it seems window units use two different kind of fans (on the same motor shaft). The hot side uses a normal bladed fan, which gives high flow but can't handle restrictions so well. The cold side uses a blower type impeller that should be able to handle a bit more back pressure.

As far as insulation... I definitely agree, since it will be trying to cool down outside air it will need all the help it can get to not lose it back outside again. I'll see what I can find locally to fit around the 5" duct.

 

[DrewsBrews]

Today I plopped the top panel on and drilled the through bolt holes that will mount the tent. Then I could bolt the panel down temporarily to trim the edges (though I haven't rivited it down yet). Since that was done I could screw down the rear hatch.

Then I measured and drilled out the rivit hole locations for the side hatches and started installing those. Just got one side done sofar.

They are meant to be installed the other way since now the drain holes are on top of the door. But with the tent overhang they would only be able to open a little over 90deg upwards. That would be super awkward only 3ft off the ground. I figure the tent overhang will shield the majority of direct rain and water pouring down the side from above. And in the end a little bit of water getting in is not the end of the world. If I need to blow out junk that collects in the hinges every once in a while, so be it.

I was going to start adding the exterior convenience lights and static airflow vents, but I could only find half of them. So I held off for now until I can find everything.. BOO.

 

[featherliteCT1]

Keep going ... looking good!

 

[DrewsBrews]

Had a storm run through today and it knocked out my shade. I tried to see if it could be propped back up (results in the photo) but it is pretty much toast by this point. It was already busted some, and just getting what use I could out of it. I still need it to keep the top panel out of the sun so it won't heat up and move around while I am drilling for rivets. Hmm.