If you plan to leave the camper on all the time, the heavier stock springs sound like the way to go. Are your air bags connected to each other with an airline? If they are, it will work against you on sway. They need to be separately valved. Also, they will fail, eventually, so have a "plan B" ready. The heavier springs would help that by taking some of the load off the airbags, reducing the effect of losing one on a trip.
I don't know all the ratings and safety margins built into axles, wheels and tires, but I run at about 10,000# on an '04 Silverado 2500HD with a set of Supersprings. Basically, that's the same truck. I'm okay with it, but if I were at 12,000#, I would want heavier springs, and higher-rated wheels and tires.
JMHO!
