Camper on a lifted pick-up
Have you picked up a camper yet?
If not, I have some experience with your topic...
I am running a Chev 2500HD crew cab long box with a 4" Rancho lift, modified air bags (to match the lift), and E rated 305 All-Terrain T/A's. I carry a 9' 2" Corsair hard wall and on the truck it's currently 12' from the ground to the top of the vent covers. I recently installed the lift to smooth out the rough riding torsion key lift hoping to actually run at 3" of lift. Unfortunately the lift keys were seized on and I am running closer to 4 or 4 1/2" of lift at the softest setting (this will be a work in progress to correct). I am sitting a bit higher than I had intended, but the truck and suspension seem to be handling the higher centre of gravity and camper height OK. I have noticed that I have to run the air bags at a higher pressure than normal to limit the side to side sway, but it is not unreasonable. I do use 5" blocks under each jack to load and unload (habit), but my "Happy Jacks" are just capable of supporting it unaided.
If you set up the truck, suspension, and camper properly, you should not have any major issues on highways and gravel roads. The truck will wallow around more with the camper loaded, but you will get used to it and modify your driving style to match. If you plan on going down narrow, rough trails on a regular basis, you should consider a small "4x4" style pop-top camper as opposed to a hard wall. There will always be compromises with a slide-in camper, you just have to choose what you are willing to compromise on.
Hope this helps...