The best adhesive for making styrofoam sandwich panels

My first thought would be to build the deck in individual 4x8 sections. So you build a frame out of 2x4's or 2x6's with one sheet of plywood on top and the insulation pre-installed between the framing members.

You would then set up your concrete piers and beams that would support the sections. If you use 2x4 framing for the pre-built sections, you would need more beams and piers, but the individual sections would also be lighter and more easily man-portable. Place the pre-built sections on top of the joists and screw them together from underneath.

When you disassemble, you just unscrew the pre-built sections from each other and the joists, take them out in one piece, and stack them on a trailer. Being 4x8, they are the perfect size to fit in just about any trailer or pickup truck and not too heavy for one or two guys to handle. Once those are removed, you can disassemble the beams and piers.

I have used wax paper over surfaces to keep it clean. Used tape over the shafts of bar clamps, small pieces of cellophane between blocks of wood that was clamped in place to keep faces of planks aligned while edge gluing.