The beauty of foam is you can determine the density just by weighing it ... The 1# per cu.ft. is standard pretty much , the 2# per cu.ft. is much more dense and solid ... We’ve even seen heavier versions of beaded foam , even more solid , not that it’s necessary ... the 1# cu.ft. is what we used on the FoamStream , with no problems , great strength ,over a wooden skeleton , and using heavy canvas (18 oz.) for the outer skin .. Use what you can get , and use it wisely ... We’re building simple camper trailers , that’s all ..

And on the other hand if the trailer wasn’t to be used except for Good weather camping (like CA, where it never rains and the temperatures are always moderate

) , then you could eliminate the foam entirely and do a Canvas over wooden rib and stringer frame (vintage Aircraft style) trailer... That would be Cool and very light ...
