Yeah I asked when we went camping together and I remember them saying that it's a bit better than half the normal miles/kWh. The site we went to was about 22 miles and 3,600 feet of climbing from their driveway, so they were not at all worried about range. If you really want to make sure you make it home, load up your camper with rocks at the campsite so you are charging more on your way home, then dump them when you reach the lowest point on your drive home.

The camper is a cabin with cedar shingles on top of a 5'x10' Harbor Freight trailer. Heavy and not at all aero haha.