your truck will suffer sticking 35s on there without regearing the rear. especially since you stated you tow alot. it will also hinder you off the line. 6in is not going to make your turnover ratio go up very much if at all. you will notice how much more difficult it is to turn with big tires though. also note that a suspen lift is considered a major modification and anything of that nature makes the overall life of the truck shorten. joints and other such steering and suspension components will seem to weaken faster after you do this mod.
please dont take it that i am talking you out of this. the way trucks look with a small lift and bigger tires makes it look mean. but with any good, comes the bad.