If you tow with a Ram 1500, please tell me how the truck is configured, and what you are towing. Please only reply if you are doing this or have done it personally.
See my signature I have a 2014 Laramie 5.7 4x4 crew cab with 3.92 hauling a loaded 6943 lbs TT. When on highway I never drive above 60mph (I stay within my TT tire limits) I always tow in haul mode and use the cruise control. The truck performs excellent whether on a flat road or on a steep grade. Last summer I drove from Quebec to disney florida and back average mpg around 12-13.