Where are you traveling from? Have you ever rved? Renting a RV for 3 weeks will be expensive. In the rv you can stay free at some walmarts. Expect around 8MPG if it is a gas maybe 14 if diesel. If you don't tow a toad which you probably want with a rental you may be limited on where you travel. You will have to have insurance. I guess if i was not also seeing if I like the RV in case I wanted to buy I would just travel by car, fly or maybe train. Having said this as an avid camper myself, rv would be my way. Good luck