Folding Hardwall Trailer

Hi All,
Although I am not planning to build a tear drop, this is the best forum for small trailer builders I have found. I am working on a design to build a folding hardwall trailer that will fit in in a 4x8x3 box on a standard folding trailer like the Benroy design. I will post some preliminary drawings soon but my initiial question is I am planning to build the walls out of 1/8" plywood sandwiching foam paneling with a lightweight framing as required. My question is what type of glue will bond foam to plywood which will allow the foam to give rigidity to the plywood? I am looking for a lightweight solution but want to stick with wood for the initial build.
Thanks.
Boffingham
Although I am not planning to build a tear drop, this is the best forum for small trailer builders I have found. I am working on a design to build a folding hardwall trailer that will fit in in a 4x8x3 box on a standard folding trailer like the Benroy design. I will post some preliminary drawings soon but my initiial question is I am planning to build the walls out of 1/8" plywood sandwiching foam paneling with a lightweight framing as required. My question is what type of glue will bond foam to plywood which will allow the foam to give rigidity to the plywood? I am looking for a lightweight solution but want to stick with wood for the initial build.
Thanks.
Boffingham