Did I understand the OP correctly in that we're worried solely about the weight of additional suspension components?
Part of your problem could be that airbags are a terrible suspension upgrade for truck campers.
After years of forums and friends saying great things about airbags, I finally bit the bullet. Dual path and remote adjustability. I've played with all manor of combinations of stableload settings, rancho 9000xl settings, Hellwig settings and air pressures ranging from 5-75lbs.
The more I air up, the scarier things get.
My experience may or may not be relevant to yours, but the 450 is plenty of truck for your camper. I might play with your suspension configuration before replacing it with a 550.
