I like the idea of driving out and then renting an RV once you get here. Bozeman is probably the closest large town where you could do that and is only 90 miles from Yellowstone. I have never done that so I don't know how you would proceed. But if you decide you are driving out this way, let me know. You would have to drive right by my house to get there. I have been to the park many times and might be able to help out in that aspect. When we go we usually just get a room in West Yellowstone and take day trips into the park.