If you don't want any screw heads to show, get some peices of aluminum (or steel) flat bar or angle about 1 1/2" x 1 1/2" x 1/16 thick and figure out where it could be bolted to existing parts of your truck to hang the roll pan. (we're talking short lengths here about 1" long.) Go down to your local Pep Boys or marine dealer and buy a small fiberglass repair kit. (they come with cloth, resin, and hardner), Determine where to put these brackets on the inside of the roll pan that won't be seen. Scuff that area up with #36 grit paper, set the metal bracket into place where you want it then use the fiberglass and resin to hold it there. Use 2 or 3 thicknesses of cloth, applied one at a time over the "leg" of the angle or bar that sets next to the roll pan, and let it extend out about 2" in all directions onto the fiberglass. Buy a pair of rubber gloves to wear becaude this stuff is a real bear to get off your skin. If you have never worked with fiberglass before, don't be afraid of it----it is very easy to work with, and very foregiving. It also stinks big time, so don't be doing this on your kitchen table.