[bestclimb]

with the aerodynamics of a barn and how heavy that thing is driver modification will yield some pretty big improvements.

Slowing down such that you don't have to use the brakes much except to stop where required will be huge.

Reducing your aerodynamic loads by reducing velocity will help a lot as well. can you go 55 in stead of 65?

depending on how long your going to be driving the f350 a cheep econ-o-box in the 500 dollar range may save some cash then sell the thing after you get your van back. please don't misunderstand as I realize a full size and very capable truck has it's place.

The performance mods, while they claim to increase mileage really don't do much, it requires a certain amount of energy to accelerate a mass and overcome the drag. performance mods can't change or reduce those energy requirements. They really only help at high power settings and that is not where economy is going to be made.