CONSIDERING NEW TRUCK

I currently tow my fifth wheel with a 99 Ford F350 2WD dually. I am considering the purchase of a 11-13 F250 4x4. (The 5er is a light-weight and the F250 can handle the weight.) My question is about bed/hitch height as well as bed side panel height. Is the trailer going to tow nose-up/tail-down? If I lower the hitch height or raise the pin, will affect clearance on the bed-rail?