suspension for towing?

[Dwaynes56&68]

I just bought a 69 lwb 1/2 ton with a cab over camper. I plan on using this as a hunting/camping rig. But the camper weighs in at 1300 pounds and thats without anything like food, clothes, or 50 cases of brew. Anyways the truck is squatting pretty good and it sways heavy around corners. It has the coil springs in back. I already plan on new bushings and gas shocks, but what about heavy duty springs or air bags? Anyone make them? I dont care how it rides, just so long as it is safe at 60 mph.