Did a run with the camper this weekend from Draper, UT to Vernal, UT and back.
We were headed for full-hookups, so no water or generator so the load was around 7200# I guess. Ran 60-65 mph and got 8.1 mpg on the way out and 9.2 mpg on the way back.
I still grin when I have the cruise set at 63 mph, we hit a 12 mile grade of 6-7% and the truck settles into 4th gear @2700 rpm and just pulls.
oh, and here is the elevation profile