Depending on the size of your Arctic Fox truck camper, upgrading your truck's suspension may be more important than engine upgrades. You will be hauling a heavy high center of gravity load in your truck bed. For suspension upgrades, I suggest installing a rear anti-sway bar to minimize sway.
http://www.hellwigproducts.com/products/big-wig/the-big-wig/
A set of upper Torklift StableLoads on your overload spring bump stops will also aid in the elimination of sway and keep the rear of the truck level by transferring some of the camper's weight to the much stiffer overload springs.
http://www.torklift.com/index.php/products/suspension/stableload
A good set of shock absorbers will also help. These upgrades to your suspension should not adversely affect the empty ride of your truck.
My completely stock '03 3500 DRW except for suspension upgrades does a great job hauling our 11.5-ft. Lance 4,000+ lb. truck camper. Traveling at 55-60-mph, it will actually gain speed going up a 6% grade in Overdrive!
Bill