5200 is an adhesive
not a glue. If you put enough steady pressure against 5200 adhered parts
, they will move against each other or separate. When I remove parts
that have been caulked with 5200, use a halyard
, wedge or other means to put a steady pull on the part after removing the fasteners. The part will come off after awhile with the steady pressure. If there is a curve to the cabin
top that you want the plywood to follow, 5200 may not hold. Epoxy will bond with a strength usually equal to or greater than the material you are gluing together. As long as you have good bonding surface free of grease, wax or other similar contaminants, would doubt that epoxy would fail. If it did fail, would doubt that anything would hold the pieces together.