I'm really not sure why anyone else's fuel tank size is of such interest to Tom. He says he really can't see any reason to do a "55 gallon tank". Seriously? And I can't really see any reason to have a smaller tank. What makes anyone else's fueling preferences "odd" to him?
My last RV had a 40 gallon tank; I hated it since my typical trip was about 350 miles, and at 7mpg, I had to make an additional stop for fuel on the way home. My current rig has a 75 gallon tank; I can now make that same trip without having to stop for fuel on the way home. It also guarantees that I have plenty of fuel for the generator if needed, both at the campsite and on the way home (for AC use).