II have a 35RLTS, is is very heavy for a SRW truck. I have the same exact truck as you, but a dually. I had air bags installed, it helped a bit. I put on MaxLoaders rear springs from tweetys.com. They sit under your factory springs, and when you put a load on the truck, they kick in. This made a night and day differenve. The truck now only drops about 1 1/2", and the ride is way better, feels much more controlled. I rarely use the air bags. Just my two cents....
2012 Cylone 3800
2011 Chevy Duramax Dually SLT