@ Huntingdog While I get your point 9 gallons is not going to keep you from getting an Aux tank. 9 gallons is about 100 miles of towing. I consider that significant.
Now in the wide open west 9 gallons may not mean a lot. But on the congested east coast the additional 9 gallons maybe enough to get you through DC and Baltimore without stopping for fuel. It may get you through NY and NJ without stopping. IT helps in the Boston and CT stretch as well.
There can be a lot of congested roads in a 100 mile span around here.
Once you leave the interstate getting fuel in metropolitan or suburban areas is a hassle. It's not that fuel is unavailable as you travel up 95 in VA and around DC. Its that you have to deal with lots of traffic and smaller stations. 100 miles worth of fuel makes it a lot more manageable.
To your point I did get an Enduraplas tank to give myself more freedom. I don't need to go another 500 miles or another full day.
I just need the flexibility to stop in convenient places and the ability to bypass the congested places.
With my Excursion I had a 44 gallon tank and never worried about fuel because I had that 1/4 tank cushion. With my smaller tank GMC trucks I have to plan more carefully in order to clear the congested areas without needing fuel.