On my last truck, '95 F350 , it came from the factory with auxiliary overload leafs that would only make contact when the truck was loaded. Since it was always loaded and needed some help I added air bags and quality shocks. At first I had enough air in the bags that it wasn't touching the overloads while sitting still and level. It actually swayed more so I let enough air out so that the overloads were in contact - much better and still gave me a little extra support on rough roads etc... Only issue was the bags always leak a little, some more than others, but I didn't have the built in compressor so I would have to add air about once a week.
New truck, '12 Ram 2500. On this truck I didn't want to have to deal with the leaking issue, and I'm still always loaded. Also, this truck didn't come with an auxiliary overload pack like the last one, even though they have exactly the same GVWR. So I added Timbrems, which are more or less solid rubber pieces that go between the axle and frame. They look like large bump stops but with the load on my truck they are in constant contact and slightly compressed. I also added quality shocks - in this case Bilstiens. Both trucks came with sway bars front and rear from the factory.
Also, don't overlook the importance of tires in the equation. Make sure you have a quality 10 ply or load range E tires. You can also go to a slightly larger tire foot print, but you have to be careful there, as you will quickly reach a point where you will actually hurt more than help. General rule of thumb is one size larger than stock, but that's very general.
Last but not least, remember what you're driving. A full size crew cab 4x4 with a camper will never be a sports car. It will always have the handling characteristics of a large school bus. ; )