PMF experiment

I am starting the process of building a teardrop (in the next few years). In the interim I want to build a pull out kitchen that will go on the front of my gear hauler (the eventual trailer for the future teardrop). I want to use the pull out kitchen as an experiment with different building processes. As one of the first steps I will need to build a waterproof box approx 18"Wx44"Lx23"H. I want to experiment with foam, plywood, fiberglass/epoxy and PMF. Here are my thoughts and appreciate feedback.
Base and 2" railing/skirt around the side will be 1/2 plywood with the underside coated with bedliner. On top of the railing/skirt (needed to affix heavy duty sliders) will be the 1/2" foam board (pink stuff). I plan on using PMF on the inside to give structural integrity (apply this to the panels before joining and then adding reinforcement at the joints). Rather than using bedsheets/canvas I was looking at using window screen material with titebond II, followed by a coat of paint. For the exterior my plan was to use fiberglass (likely 6oz) with epoxy, coating that with bedliner.
Anyone used window screen material in place of the canvas? (I will do a few test strips before fully going this route If I proceed in this direction). My thought would be to compare PMF with window screen with the fiberglass for durability and lasting adhesion (obviously not apples to apples comparison since one will be interior the other exterior). Am I overthinking and should just use canvas instead (I just like the idea of tinkering with something new!)
WIll PMF in the inside and fiberglass on the epoxy outside give enough structural integrity to the foam board as to not collapse. I obviously don't plan on using it for standing on but likely a water jug will sit on it at some point. Thanks for any thoughts, encouragements, and redirections =)
Base and 2" railing/skirt around the side will be 1/2 plywood with the underside coated with bedliner. On top of the railing/skirt (needed to affix heavy duty sliders) will be the 1/2" foam board (pink stuff). I plan on using PMF on the inside to give structural integrity (apply this to the panels before joining and then adding reinforcement at the joints). Rather than using bedsheets/canvas I was looking at using window screen material with titebond II, followed by a coat of paint. For the exterior my plan was to use fiberglass (likely 6oz) with epoxy, coating that with bedliner.
Anyone used window screen material in place of the canvas? (I will do a few test strips before fully going this route If I proceed in this direction). My thought would be to compare PMF with window screen with the fiberglass for durability and lasting adhesion (obviously not apples to apples comparison since one will be interior the other exterior). Am I overthinking and should just use canvas instead (I just like the idea of tinkering with something new!)
WIll PMF in the inside and fiberglass on the epoxy outside give enough structural integrity to the foam board as to not collapse. I obviously don't plan on using it for standing on but likely a water jug will sit on it at some point. Thanks for any thoughts, encouragements, and redirections =)