NyBilly, Yes, I do have the XL which is equivalent to the Suburban. Not sure how much difference that really makes. But, I'm really disappointed that you had that much problem with a 5500#, 26ft trailer.
Honestly, I started out purchasing the Yukon XL for the features, 3 seat room and room behind the 3rd seat. Wasn't planning on replacing my Jayco 14SO popup, but started thinking about it after the fact.
Campfire Time - Yes, it is probably 8300#. In researching, I've found both 85K and 83K listed. The Manual shows 8500# on the page you listed in your note, but online I've also seen 8300#. If you take the GCWR and subtract the curb weight, you get 8464#. It is the 2WD version.
I did get the max towing package, and looking at the Detail Info on the VIN locater, it shows KC4 (Oil Cooler), GU6 (3.42), NHT (Max Trailer), JL1 (trailer break controller), KNP (Trns Cooler). But I will verify the stickers as well to make sure. Thanks, I did find the Hitch rating in the manual. Must have missed that previously.