Advice for first time rv buyers

Wow! Thanks for all of the replies. I have to admit that I am surprised that each reply warns against fulltiming with kids. I guess maybe I am shooting for the almost impossible. I just thought because of how often we move it would be better than what we spend on moving expenses and rent. Rent here is expensive at $15,000 a year and each move costs thousands. Winters are not as cold as you might expect. We live in what is called the banana belt of Montana, near the Flathead Lake that keeps temperatures on the moderate side. A little background on life circumstances may be in order, here. My husband lost his job in Pennsylvania about a year and a half ago. We came to Montana so that he could go to school for forestry. So we have already done what most would never do with kids.
The salesman (I know he is trying to sell us a rig) said that the Keystone Fusion was made for Montana's weather. Is he just trying to sell it to us or is he telling the truth. He said we would have no trouble with lines freezing up because the basement areas are heated.
I can feel my excited bubble popping right now and I am feeling sad. I thought that this could mean freedom from budget breaking rent and mortgage payments. I respect all of you who are giving me advice and I really appreciate you taking the time to give me a dose of reality. So glad that we have the internet where we can connect with people who have been there, done that! Thank you!