I call BS on this- no way he averages that over a long term. For a trip, sure. But there are too many variables to compare to others MPG, we don't know the weather, wind, grade, tires, speed, etc.
My best tank ever was 22 mpg, cruise set at 70 driving across Iowa in summer. My Hwy Average is in the 18-19 range, and closer to 15-16 in city. I log on a per-tank basis.
I have a 1500 with v8, 3.42 gears, 6 spd tranny. There is nothing you listed I wouldn't be more than comfortable doing with my truck. And you have 2 extra gears which will only help you.
There is no way I'd daily drive a 2500 unless its for work.