When camping in the Qartzsite desert, I'd fill up a few 5 gallon buckets with water at the spigots, drive back, then set one of them up on a rung of my step ladder, leaning up against my tt.
Using a 1/2 inch ID vinyl tube, I'd start a siphon flow and stick the tube into the tank fill port. As it empties, I'd dump more water from the other 5 gal containers until all had flowed into the TT tanks.
Works for me, but it's a struggle. But then I like a challenge.
And it's much easier than breaking camp and driving the tt to the spigots.
2011 Dodge Ram 1500 HEMI Quad Cab
2011 Jay Flight 26BH