Try it out in your driveway or an RV Park. Don't plug in, don't attach the water hose, don't hook up the sewer. How long can you go?
Now you will have a better understanding of what you'll need for dry camping.
For me, I could go a week with one my group 31 AGM battery and a tank full of fresh water with no problem. But, I camp simple - no 110v appliances, puck lights and lanterns to supplement lighting, propane stove, extra blankets and Mr Heater Little Buddy propane heater if absolutely needed for heat, supplement water supply by using campground facilities and campground water when convenient.