Rental tow vehicles (Enterprise truck rentals etc)

While I wouldn't use your Yukon for extensive traveling with a heavy trailer, I think you'll make it home with the trailer. Just baby it. Drop to low gear on the hills and use half throttle, go as slow as you have to. If you don't work it hard, it should be fine. You're going to drop some $$ on a truck rental that sounds like could be much better used on something else.
Are there any real mountain passes you have to cross?