fwiw...
This past Labor day weekend it was interesting watching the temperature gauge on my GMC 2500HD gasser while towing the 2005 TM 2720 wet and loaded for bear, with two motorcycles, 20 gallons of gas, generator, and a bunch more heavy stuff in the 8 foot bed up to Bass Lake, Ca (elevation 3380 feet) with an outdoor temperature temperature of 104F.
Good thing it was 5PM, otherwise the outdoor temperature would have been a little hotter.
On any uphill section that I was on, I was able to accelerate any time that I wanted to. Under no circumstance was there a reason to pull over to allow others to pass, as I was towing at the speed limit of 55 (I'll never admit to driving at 60 in California). At times I passed minivans that were not towing. Perhaps they just liked to drive slow.
Nominal transmission temperature is usually 175-180. This time I saw it hit 210 at times. It might have hit a bit more when I wasn't looking.
I was going to weigh it on the way home but ran out of time.
I am happy with my configuration. It does all that I expect it to do.
I would not recommend a small tow vehicle to go where I go. California has some serious foothills.