Plug the holes with hole plugs. Do a search for "3/4 hole plugs". (no kidding) Example here:
hole plugsYou don't need to do much.
I built a bed from 2x8 and 1/2 inch ply. Size to fit available mattress. 1x3 inside 3 inches below the top edge holds plywood in place and leaves a 2 inch lip to hold mattress, too. good storage under.
Everthing else is trim. Cheap "blue tarp makes awning.
Custom toilet seat from Cabela's fits a plastic bucket. (line w/ plastic bag for easy clean up)
Get a hibachi or cheap gril. Keep charcoal dry and fresh in plastic bucket and cap.
Carry drinkng water by gallon, up to 5 gal.
Use paper plates.
Call me when the fish are running.
:W