I agree with the one step at a time and then re-evaluate the situation. The truck as it left the factory was not setup for carrying a heavy camper for hundreds of miles but more for comfort.
I would start by examining the truck with the camper in the bed. If the truck squats in the back then you need more spring lift. SuperSprings are the easiest way to add to the load capacity of the factory springs and they do not engage unless their support is needed. Air bags help more when one side of the camper is heavier than the other as you can add more lift on one side but they do break and they do need to be adjusted for your truck and the load and it is not all that easy - check the posts from people with air bags that are not happy with their ride control.
Be sure to have your tires at their maximum PSI as sidewall flex will be much greater with a camper load. I changed out the factory tires that were rated at 3195@80 PSI with ones rated at 3750@80 PSI and there was a noticeable improvement in control with the new tires.
The shocks are going to be shot unless you replaced them in the last 20,000 miles. Rancho 9000XL or Bilstein 4600 or 5100 shocks are good for use with a camper. The shocks by design will dampen the movement down on one side of the truck when entering a turn and at the same time the shocks on the opposite side will dampen the upward movement of the truck.
Another add-on but the last to consider is a rear anti-sway bar and a heavy duty one that is 1" or larger in diameter.
Be aware that trucks are different from year to year and among different makes so what works with a 2009 Ford or 2005 Ram or 2011 Chevy is not going to necessarily be directly applicable to your truck.