I have a power jack and only using it to unhook and hook-up is the only power drain for the jack. We have two batteries, wired in parallel(12v), and use the jenny about every 2-3 days to charge them up. I check the batteries with my multi-meter everyday to monitor our usage. I don't let them get below 60%. DW's only complaint is no hair dryer without generator.
Water: we do the extra water jugs with transfer pump. We use one of the jugs out doors for washing up, filling dog dish, etc. Works great.
On you first trip monitor your usage, water and battery, and the following trips you will be able to adjust to make your camping "just the way you want it"...