It seems, unless you go toy hauler you're going to be looking at 40 gallon or less. Of course, there's always the option of putting in a bigger or 2nd tank.
:B 2013 F-250 4x4 Crew, 6.7L Turbo Diesel, 5000lb Air Lift rear bags,
Equalizer 1200/12K Trunnion Bars
2015 KZ MXT 303 Toy Hauler:C
2013 Yamaha FJR 1300, 2 dogs, Him & Her:C