We will be in Yellowstone Mid Sept. I was wondering if I should make reservations or not. Sounds like more people are camping there latter in the year from the posts I have read. Since we are making a lot of other stops along the way I hate making reservations unless I have to. Also considering I cant run generator at night I was wondering how long I can expect to run my MH furnace on battery alone. My Class A 31' has 2 27 series marine deep cycle batteries. Just bought a third series 31 850amp deep cycle battery to take along as well.