Yu should carry a "Water Thief" with you. It is made out of rubber and slips over those faucets that have no threads. Then you hook a garden hose to the water thief and fill as usual. I carry a 6 gallon jug and strap it to a folding hand cart and haul my water back to the MH and then I use a spare 12V Shur flow pump with hoses to transfer from the jug into the gravity fill of the tank. A 6 gallon jug is to heavy to man handle so that is why I have a pump.
Here is a link to what he water thief looks like.
Water thief