Truck bed rubber mat

I found a source for 1" 25psi XPS foam insulation board. I'm debating getting 1 sheet and framing it into the bed with plywood or something so it wont shift as well as adding support for crushing of edges, or get 2 sheets and cut to fully fit bed, or buy 1 sheet and leave alone. Either option selected, I'd add a rubber mat over. Another option is to add 5mm luan plywood to avoid dents from camper corners when setting down.

This stuff is currently $17/ea so its light, easy to cut, and fairly cheap compared to all other wood options.