Truck stops are the way to go. Getting fuel comes down to easy in and out access.
saving a few pennies is secondary.
Once you get hung up trying to maneuver around a regular station, battling cars and unaware oblivious drivers you will understand there is none of that nonsense at a truck stop.
Don't be a tourist get your fuel and move/park your rig before shoipping or anything else.
An auxiliary tank does allow for a lot a fueling flexibility however unless you a full timing and aux. tank maybe over kill.
