just add DEF to your DEF tank when your 'bars' show less than 1/2 a tank - no worries, you don't use that much fluid, even when traveling a lot, and W*mt and most any fuel stations have either gallon jugs or 2 1/2 gallon jugs.
I've carried some extra with us from time to time, if traveling really long distances, but the reality is that you don't' need it very often, and it's available almost anywhere - you have to fill up on diesel a LOT more often, anyway!
'14 Palazzo 33.3 bunkhouse 34' diesel
KingTailgater2 Dish HD, 100w/5a SOLAR, BlueOx
100,000+mi since '14 - US, Alaska, Canada - Hiawassee, GA! (also, '14 Gulfstream Amerilite and '07 ForestRiver Rockwood) : )