I'm stymied right now, in terms of building space, so I have been exploring design ideas.
One of the things I've been thinking about is using a slide - about a 12 inch slide out on one side to get everything in it in the size of exterior I'm after.
How would you construct things so as to have a strong slide when the trailer is a box (not a tear) and is constructed of skinned foam? One of the goals here is absolute minimum weight.
The walls / floor / ceiling would be constructed of (depending on location) 1-1/2 or 2 inch foam skinned on both sides by 1/8, 1/4 or 1/2 inch ply. The slide area would ideally keep this construction, but I don't see how you make it strong and prevent flexing. Or perhaps it's not really an issue. I just don't see where the strength would come from, unlike the "box" of the trailer, which is strong due to its shape and distribution of forces.