If by "put a camper on" you mean one of those slide in campers, the power wagon comes with specific instructions not to. It can be done, I saw one in town yesterday didn't lean or sway around turns. If you mean a topper thing to enclose the bed then ignore that.
Legally speaking, air bags can not change the door sticker payload unless it were to be recertified. Luckily for us there is no law (that i have found) that says you can't go over that number. If your truck is sagging badly, swaying, etc. while hauling stuff the police can sight you for that. Highway police look for over loaded axles. Axle rating on this truck is 9000 pounds or so in the rear.
Real life example of the payload silliness on a power wagon. One time I had 4 adults in my truck and a big cast iron furnace thing. If I had to guess the weight of the adults 2 were 250lb and 2 were 300lb, the furnace weight 500lb, add that up 1600lb. Subtract 150lb for the driver that is calculated into payload rating for a total of 1450 of payload, if I remember correctly for my truck that's over weight, yet it didn't squat a whole inch. It's a heavy-duty truck! How can 4 adults and a little weight in the bed over load it?