If you have the rear overload springs replace the stock bumper stops with torklift stable loads
http://www.torklift.com/products/stableload.phpMy F350 with the Camper package came with rear anti-sway bars if yours doesn't have them get them.
What tires are on it? they need to be load range E and be rated above 3150 (mine are 3750)
How old are the shocks (oem are junk)you may need new beefier ones
You Should not need to be running 80 psi in the bags if the truck is set up correctly My 1055 on my 350 runs fine at 30 psi