I tow a 24' Passport with an 03 Tahoe, which loaded with all my stuff and full tanks weighs 4800 on the axles plus about 800 on the hitch. It's really the heaviest/longest trailer I would want to do with it. It is comfortable but a bit tiring when on hilly or windy roads. My use is almost exclusively hilly/windy, though.
Trips I've commonly done with it are Portland, OR to Big Sur, CA; Portland to Anacortes Wa (several times), Portland to US101 Oregon (at least once per month), Portland to Tofino, BC, Portland to Boise.
The brakes are great, the 5.3L is fine, but the 4 speed transmission needs another gear and the rear coil spring suspension is too soft and requires a lot of weight distributing hitch to keep from porpoising. My option package is 5.3L, 4wd, 3.73 gears, Nivomat rear shocks, P3 brake controller, typical round bar hitch with 1000 pound bars and friction antisway. The exhaust/intake noise is loud when going up hill. I have had absolutely no heat issues. I run synthetic transmission oil.