Our Itasca Class C has an 18 gallon propane tank ... and I wish that it had come with a 23 gallon tank instead.
We prefer as large a built-in propane tank as possible in a Class C, for two reasons:
- Gasoline fuel is the easiest to find, diesel fuel is harder to find than gasoline fuel, finding potable water is harder than diesel fuel, and the capability for refilling of a built-in RV propane tank is hardest to find. Even though the little 5 gallon propane tanks can be exchanged for full "everywhere" ... even a couple of these is not nearly enough to be ready for dry camping anywhere anytime in a Class C, and of course Class C motorhomes use only built-in propane tanks.
- We don't care for a cold motorhome, so we use our propane furnace for maximum comfort as desired.