So I have a 2008 Yukon XL with the 6spd transmission. just bought June 2022. Towed my #3500 lb boat last summer with little issues. This winter I was towing a 2 place enclosed snowmobile trailer with 2 sleds on a fairly flat road. It seemed to me that even in tow mode, the thing shifted up and down more than I would think. I was under the impression that in tow/haul, it kept the truck in a lower gear to stop a lot of that. Is that right? Seems with a 2000lb trailer, this should have been a cakewalk. I't just seemed to struggle. My son in law towed the same trasiler with his Dodge 1500 without trouble. Any suggestions?