7k dry TT means:
8000-8500 pounds loaded
1000-1200 pounds of tongue weight
I expect your Yukon would be exceeding the GVWR, GCWR, receiver rating, and rear axle rating when loaded up with people inside and TT connected. You have a lot of power and a good transmission. Suspension is your weakest link based on ratings when it was new. Towing with anything 10+ years old will depend far more on condition and how it was maintained.
I recommend sticking to around 6k dry TT for most half tons because of all the other ratings besides manufacturer tow rating.