Stop in for a cup of coffee

I have thought of a large tank for the bed of the truck. BUT that would cut down on what I can haul.....Seriously considering driving the 66 To Carlisle next year, pulling my 8 ft aluminum trailer, with a AUX tank on it, with a fuel line going to the car. The tank in a early A body is very small for a v8 engine...IMO. I am hoping for 20+ MPG in my Dart. I bet I will get there with the engine/ trans combo I have setup....