This is my first post. I now have an Escape fifth wheel pulled by an F-150 with the little 2.7 liter engine. On long trips, 3000 to 5000 miles I get 14.5 to 15 miles per gallon. I’m looking to get an Alaskan. I know I need a heavier duty truck, but all the F-250/350’s have big V-8’s that get 15...