As with ANY camper, for first trip, go somewhere close to home. Watch the Energy Graph for the utilization and that will start to tell you your range pretty quickly. Before you hitch the camper, look at the energy graph and see what your average usage is and use that to compare to what you get when towing.
If you are seeing it increase from ~250 to ~1000 wh/mi, then you can guess what your range is going to be.