Dave, sure you can, Jim already mentions his project. The only consideration in the construction, is to dry fit panel/ skin of your choice, wood glue on perimeter 2x2 frame and use "foam safe Liquid Nails or DAP caulk placed zig-zag across the foam. Need solid flat surface to lay panel, place 1x or plywood and weight to compress the unit to dry. You don’t want the skin to delaminate from the foam.
I build specialty insulated doors as Jim descibes for attic knee wall access and even basement/ bulkead units, of coarse the build is far more robust in frame configuration and 3/8 or 1/2" plywood is used.