We just did a 6k mile trip through the southwest, including many of the tough passes in the rockies. The entire trip was a dream from a towing perspective. NOT ONCE did the truck labor (or even work). It was also stable under all conditions we encountered. Granted, I'm towing fairly light, but I was at max on payload.
Averaged 11.5mpg over the 6k miles, and 12.1mpg for the last 1100 miles from Kansas to SC. Beyond my expectations! The mileage was a bonus, the real value is in the effortless, low rpm towing.
Weak point was braking. If I had been towing your weight, I might have had concern.
I love the truck.