I have a cheater way of doing something similar. I put the winterize hose into the water jug and set the valves appropriately, go outside and take the shower head off the outdoor shower and stick the bare hose in the city fill inlet. Turn on the pump and presto, pumps the water into the holding tank. This is easier if the hoses are well placed; my winterize is inside so a bit of running in and out, easier for TTs that have all the connections close together.
I'd like to claim this trick as my own, but like most good tips I saw it here on JOF.