Camp woof will probably have the same issue I have. If I don't put a 2x8 across the front of the bed, my rear doors will hit the dually brackets.
Camp woof, you may want to get a couple eye bolts to use on the Bigfoot tie downs. If not the tie downs will hit those fenders. I used 1/2" but had to drill out the Bigfoot tie down holes a little. 7/16 or 3/8 would work. I used machinery eye bolts that have a shoulder on them from Amazon. Assume you're Using Fast guns. Might talk to your dealer to see if they have an alternative.
I also cut 5/8" plywood cut in 4 pieces to completely cover my bed, including in front of and behind the fender wells. The Bigfoot is supported by the walls and I didn't want the edge of the camper sitting over the "low" part of the truck bed corrugation. I then put a full coverage rubber bed mat over that.