Does my 5x9 on a 4x8 trailer qualify? wood content- galley floor, galley wall, and wylie window frames. The galley floor is stepped down from the main floor and takes a beating. the galley wall could have been foam but I needed to finish quickly for a trip. I did use some hollow core plastic deck boards for the galley door hinge mounting. Everything is canvas-foam-FRP(glassboard) 2"foam floor,1" foam walls, 1" foam roof and even 1" foam door without any wood.

No testing before a 3000 mile trip with speeds up to 85 mph

Just wanted to some thing different and light.(640# with 6" foam matteress)
A person could save some weight by using 2"foam and FRP as support plates glued on at hard points.