For what is worth, I have a 2017 Dodge 2500 6.7 CC, 4x4, 34" AT tires, and everything is stock. I do have a truck cap, Rhino Rack and Foxwing awning. I've taken two trips from SC to Montana for extended fly fishing trips over the summer. Average crusing around 70 - 75 mph I get around 21 mpg in...