I just recently picked up a bronze 1999 escalade in excellent condition for the primary purpose of towing my drag car to the local racetracks. I was originally looking at tahoes and yukons, but found a good deal on the escalade and figured that its pretty much the same thing as the OBS yukon's with a few extra creature comforts. I love it so far!
I am looking to lower it, but I am looking to retain the stock wheels and tires (currently wrapped in 265/70r16's). I have done much searching here and around the web, and it looks like the beltech 3/2" kit might do the job (or th3 3/3.5"). I would like to go as low as possible while still being able to retain the stock wheels and tires without rubbing. (I will eventually upgrade to some 20's later, but the stockers have new tires right now and I still like the way they look

.)
Is this 3/2" or 3/3.5" drop going to allow me to retain the stock wheels and tires without clearance issues? Can I go lower without clearance issues?
The next main concern is that I need to be able to tow ~5000lbs without rubbing. I do not believe that I have any factory form of load leveling. Can anyone recommend a setup that will work with the drop and allow me to keep the rear end from squatting while towing, while still being able to keep the truck level to the ground when not towing? Perhaps rear airbags or some sort of air shock?