Wow, has it been over a month? The project stalled for one reason or another, mostly because I hadn't decided on windows/doors etc.
But I decided I'd build it as I went.
Here's a picture of the bicycle on the trailer, with one of the walls being held in place to give me an idea of how much room I'd have.
Here's a closeup of how much headroom I'd have (minus the spars).
Here's a distance shots of the walls being held in place by some scrap wood. I like the profile.
Here's a bird's eye view of the progress. I haven't connected the walls to the floor because I haven't decided if I'll make the whole thing rotate/lift up or just build a traditional hatch.
The spars are 1x3 yellow pine. At the location where I would put the hinge if I were building a traditional hatch, I glued some red oak 1x3's together to form 2 2x3 spars so the hinge screws can have a truly solid foundation.
Up next is to completely fill in all the spars, and see how much the walls+spars weigh, to see if it's feasible to make everything above the floor lift up.
FYI, the 5x8 trailer, made of 2x3 angle on a 3500lb axle weighs 330lbs, just the steel itself, no subfloor etc. I'm hoping that when all is said and done, it'll weigh less than 600lbs, especially since I won't have a galley.