Been there, done that...got a different TV to prove it.
We had a Yukon XL and we thought it would be great to tow our Rockwood 8313SS. Unfortunately, as much as we enjoyed the TV we had to upgrade if we wanted to have a large SUV to pull the TT. I had a pickup truck (F150) that was geared and set up, but it was not comfortable for the kids or the family dog. I have since upgraded my TV to an older Suburban 2500 that is safe for pulling the TT, comfortable for the children and pet, and overall a much better towing experience.
Your '12 Yukon XL will tow a TT nicely, just not a bigger bunkhouse. You may be able to get away with a Hybrid or a smaller BH, but I would not venture into the realm of the 800+ tongue weight and TT that have gross weights over 7,000#.
Good luck and happy hunting.