I used coroplast in college for various projects. I quickly discovered that cross-layering the corregations increased the rigidity significantly. I would always use twice as much material at half the thickness of other students, but my structures were always much stronger than theirs. Well, until the instructor caught on and started limiting the total material we could use. Then I started reinforcing with bamboo skewers, but I digeress.
I like this idea, one of the hardest things to find in the wilderness can often be a flat place to work. I am sitting here thinking of a way to make it more packable. Considering a rollable cutting mat, or similar thin plastic.