Options exist
Option 1: Fill at destination, used "Canned" water on voyage (Jerry cans or gallon bottles ISIDE, heat water on stove if need to do dishes)
Option 2: Fill but do not activate water pump See option 1 for what to do on road.
Option 3: Fill, fill lines, (turn on pump) and activate water heater.. This I knwo, if it's operating (on propane) and you have propane, it WILL NOT FREEZE (same is true if parked with shore power and on electric) very hard to freeze water when a fire is heating it to 120 degrees.