Looking around it seems like there are two kinds of teardroppers, those who buy a pre-made trailer and those who build their own. We fall into the middle – we have a home-built trailer that was built by someone else. As a result, we’ve come to find that there are things we need to do to make the trailer more useful and more comfortable for us.
Here is “Bubbles” as we bought her. She sits on a 5 x 8 (approximately) utility trailer frame, quite a heavy one. Not sure of the weight (getting her weighed is on m ‘to do’ list.) Construction is (according to the builder/seller) Marine Grade plywood, 3/4 sides and 1/4 top, all wood. She had a coat of some kind of marine varnish that we found totally inadequate to protect the wood so we are in the process of coating her with successive layers of polyurethane spar varnish.

A couple of things ought to jump out at you right away: First off, she sits very high. Not sure why she was built this way, except I think the builder might have had ideas of taking her off-road. Nevertheless, the galley counter is chest high on me and so high as to be darn near unusable for my wife. The excessive height also puts it in a distinctly canted-down stance, which is not good for handling or wind resistance (though this is helped a little bit by using a 3 1/2” drop hitch, reversed.)

The second thing that should hit you right away is that the axle is a mobile home axle, sometimes called a “Dayton” axle. It uses a hubless 14.5” wheel. I’ve been cautioned that the “wedges” that hold the wheel to the hub can loosen unexpectedly, so I check them every time I get ready to roll. No problems so far, but it’s not something I like to have to do.

I’m interested in either converting the axle to a more conventional hub that can mount a “real” wheel, or swapping the axle out entirely for a conventional trailer axle. At this point, a full axle swap seems to be the best way to go, because it would solve 3 problems:
1. Where the old axle is a “spring over” axle setup (which raises the trailer) the new one would be a “spring under” which would lower the trailer.
2. As you can see from the pics, the mobile home axle is MASSIVE and the hubs are large, cast-iron looking things with brakes in them (brakes that aren’t hooked up.) Removing this oversized axle would help me reduce weight, and of course
3. Going to a conventional axle would give me a conventional (brakeless) hub that I can mount “normal” trailer wheels/tires on (which will reduce the weight and make it possible to mount a spare to the frame.)
You can see the "spring over" design here as well as the massive thickness of the Dayton axle:

The final point in favor of a full axle swap vs. a hub conversion is that it looks like I can get an axle for ~$150 while all the parts necessary to swap the hubs would cost me at least $100 altogether, so there’s not much of a money advantage to keeping the Dayton axle (especially when considering all the other negatives of the Dayton.)
We also have some other ideas such as putting on more stylish fenders and revising the electrical system (right now it’s just a 120v plug on the left side that runs to a power strip in the galley.)
So, with that as preamble, my questions are as follows:
1. How difficult is an axle swap with a spring-under change? I’ve never put a trailer together so I don’t know. My thinking is that if I can unbolt the old axle it will just drop free, then if the hubs on the new axle are small enough to slip over the existing leaf springs, I may not even have to remove the leafs. If I do remove the leafs, I would think they’d be easy to put back together. Then the new axle would go in the same position as the old one, except that the axle would be on top of the springs and of course the U-bolts would be a different size (smaller) and would face downward instead of upward.
Is there anything else I need to consider with an axle swap? Is ‘true-ing’ the axle (that is, making sure that it is not angled to the left or right) difficult?
As far as weight capacity, I’m thinking a 1500lb capacity axle should be plenty and offer a nice margin of safety. I know I can get one of those new for about $150 and if I find a used one I can probably get it for less. It would be nice if I could get one with a bolt pattern that matches my tow vehicle (2007 Toyota 4runner) but that’s not really necessary. I think I would prefer a bigger (15”) wheel to a small 13” or 14” trailer wheel, though, but it will really depend on what is available on the axle.
2. With regards to the wood, as I said, we are in the process of putting spar varnish on it now. We have one coat and will probably put a few more coats on before next year. Is there anything else we need to do to protect the wood?
3. One thing the trailer could really use is better ventilation. Can someone recommend a good vent that we can install on the side? We don’t want to put one of those big rectangular skylight- type vents on the top (the ones that tilt up when they open) because it will ruin the looks of the trailer and also because the entire roof surface is curved and we would be worried about sealing it watertight. I’m thinking a couple of small, round, possibly shrouded vents on the sides near the very top, maybe 3” in diameter, would work. Does anybody know of such a vent or how we could find or make one?
Thanks in advance! I will of course post our progress as it goes along!