My nephew uses a siphon system in is old FWC shell. he put in an external tap, and starts the siphon, the just leaves it operational till he‘s done with the jug. Works pretty well.
I saw another thread like this a while ago where everyone was focused on the battery powered jug top pumps, and Mario at AT Overland added a post where he said they used to use those, but had problems with the pumps malfunctioning and people coming back to a camper full of water as the jug emptied itself. Don’t know how common that is, but …