OK friends. I've read fuel mileage for a 35' gasser with the v-10 Ford engine pulling a 3500 lbs toad will be anywhere from 4 to 9 mpg. This is average traveling, not all level and not all hills. ...
Chances are if you start driving by your wallet, your trips will become worry and not be any fun. Keep the accelerator off the floorboard and drive off the top half of your tank. We have the Ford F53 chassis an tow a 4 door Jeep. Not nearly the towing power the previous 425 hp Cummins had, but it gets the job done.