On a single G-24 battery you should be able to go 2-3 days IF you're frugal with your power. In our pop-up we used flashlights and lanterns at night. My guess is most people get 1-2 days before the battery is depleted.
If you use the shower in your camper and wash dishes you can go through 30 gallons of water in a day. Campground showers and paper plates will stretch your water supply. DW & I can go 10 days or so on the black tank.
Now, add dual batteries, LED lighting, solar panels and / or a generator and it's almost infinite. If you have a way to replenish your fresh water and get rid of the gray then you can really extend your time in the boonies.