As Rando said towing capacity is a good measure of what your truck engine and transmission can pull down the road. I have a 2011 access cab Taco 6 cyl, auto, 4X4 with tow package and Fleet at about 300 lbs over weight with full gas, water and gear. I have upgraded KO2 E tires, Firestone air bags and shocks and with over 60,000 miles I have no problems of any kind with mixed freeway to off road driving. I do not drive over 70. Because I am asking the truck to do some work I do maintain it more than would otherwise be required running full synthetic and changing fluids and filters more often. I would suggest that the camper weight may not be the problem, but having the added weight of the camper can accentuate a already existing problem with how your truck is running that you might not even notice otherwise.
As you can tell from the other threads, this whole weight issue is a conundrum, it is not defined how weight is established in law or rule or even anything published or available from the truck companies about how they do it. There have even been two pickups built where the only difference between the trucks was the springs and one was a 1/2 ton and one a 3/4 ton. At other times whole sections of components were different between different weight rated trucks. One year the only difference in axel weight was a different set of wheel bearings. One year Chevrolet had 3/4 ton models with GVWR of 9,300, 9,500, 9,900, 10,000 lbs. and 1 ton sharing the same frame, front axle and front suspension, brakes, engine and drive train with GVWR of 10,400, 10,500, 10,700, 10,800, 11,000 pounds and the only difference with the 1 tons was an extra set of leaf springs and 18" tires with a higher load rating. The only thing that we do know is that the load rating is set by the weakest components on the truck and politically by general added cost and CDL requirements in some states for going over a certain poundage. Because manufacturers want trucks to ride like a car I think the weakest components on most 1/2 ton trucks for carrying weight are the springs and tires and it sounds like you have addressed that. Although I think most truck owners believe that I could modify a truck to increase horsepower, increase MPG, shorten breaking distance, better the sound system or many other changes there are still a lot of people that do not believe that modifications can safely increase the load carrying capacity of a truck. I am not one of them.
