Put a 30 gallon auxiliary tank in the bed for the convenience of being able to fuel where I want while travelling. Pilots or Flying Js and the like are not always available and trying to get in and out of a service station filled with passenger vehicles and you're pulling a trailer can be a PITA. After the first couple of trips the extra tank was added. Usually we now wait to fuel after we have stopped for the evening. After unhooking, we'll go get a nice meal, fuel the truck, and be ready to go the next day again.