7,000 - 8,000 lbs you are towing? Tahoe is too small, short wheelbase, not enough suspension or brakes. Even if the drive train could haul that weight. You need stability when towing. Don't let the tail wag the dog.
I had a 3/4 ton 2004 8.1 Suburban. Gas guzzler. Oil guzzler. Towed smaller trailer pretty well - about 6,500 lbs. However, getting into high altitude - above 8,000 feet of steep climbing - there were issues. The issue was the transmission, not enough gears when towing up steep, slow, curvy inclines at high elevation.. Even with that kind of power 1st gear was too much, 2nd was not enough - so it was hunting between gears. Most gasoline engines are not forced induction so lose a lot of horsepower as elevation increases. Most modern diesel pickups are turbo charged - thus lose less horsepower as elevation increases.
I now have a 2012 6.7L Ford Super Duty turbo diesel. Loved it, until the turbo charge tube blew off a month ago 250 miles from home, 50 miles from nearest dealer, in the middle of the desert towing my 5th wheel. It's fixed now, and I now carry a spare charge tube (known issue). I'm no longer in love with it, now I like it - hoping it doesn't break down like that again.
Cost of ownership is probably higher with a diesel.
