Building a trailer frame.

[loaderman]

Not a foamie, just hoping you out of the box thinkers can help me.

I am designing a 3.5 by 7 foot trailer. This would serve as a base for a tent top. The walls would be about 14 to 16 inch. The idea is to build the box with hinged flaps for a lid then when opened up put a tent on top.
I am doing this to have a roomy 9 by 7 area, decent beds on both sides, ability to stand in the center and it would be lite. Also easy to tow as it would only have a very small frontal area.
Weight is a huge concern. With all the gear for 2 people I would like it to weigh about 600lbs. The trailer including the box at 300lbs or less. So I have 300lbs for cargo.
Any advice on the frame design would be appreciated.

I was thinking of a modified pico lite frame. Using angle iron and making it shaped like a boat trailer. I would put a piece across the back then about 2 or 2.5foot from the back. The sides would angle in at about 4 to 4.5 feet from the back to form the a at the front, no one would be standing within 2 feet or so from the front of the box.
The 1/4 inch plywood sides would would.be glued and bolted to this angle iron frame which would add strength. The 1/2 inch plywood floor would be glued and screwed or bolted on.

What size of angle iron should I use? A 250lb person will be standing on the floor.
Tanks for any help you can give.

Any other better ideas?

[John61CT]

If you can afford aluminum C-channel profile and an experienced designer/engineer that will give the best result.

Just for a nice rigid but lightweight lower chassis frame, the superstructure can then be trial and error.

[Hamilton Felix]

My goal is also very light weight. If I did not already have something for free (my other goal is very low cost), I would be looking at an aluminum trailer. As it is, I am modifying the lightweight steel frame from a 1988 Jayco pop-up that we scrapped. The Jayco is made mostly from very light C channel, no more than 1/8” thick. I think I can make my mods using old bed frame lightweight angle. My goal is to make a light duty flatbed that is exactly the size needed for the foamie I intend to put on it. I see no reason to use any “normal” weight angle from my scrap pile. Nothing here requires that strength, and I don’t want the weight.

[greygoos]

Why dont you use the same kind of platforms that some of the motorcycle campers use. They are very lightweight or as light as you are going to get. I would think that you would need a whole lot of angle iron to support a 250 pound person on a 1/4 inch of plywood. If you start with a small trailer even a smaller harbor freight you could build out over the frame with a folding platform made with 3/4 inch ply and a couple of stabilizers when you open it up. A sheet of 3/4 is about 70 pounds. You would be towing less than 200 pounds.

[Zzyzx]

Well, you could consider going up to a 4'x8' trailer since off the shelf materials come in those dimensions and that is close to your original size.
If you want a very lightweight aluminum trailer, you might look at the Northerntool 4x8 utility trailer.
It is 200 lbs shipping weight, has 1170 lbs load capacity, and is $650 shipped.
I have not used one of these trailers so I cannot comment on its quality, but it gets good reviews.
It is a bolt-together trailer which avoids the problems of welded aluminum but may not be as rigid.