I can appreciate your ambition, but that is about where it stops. First off, buying an RV of that vintage, thinking you are going to be able to turn the key and go is far from reality. Just tires alone will cost you 2K. Who's to say what will happen to a 20 year old RV while you are on the road. New transmission, 4K. New engine, 10K and the list goes on and on. You would be one thrown rod from being homeless. Not a good plan by any stretch of the imagination. If it were just you, then I say go for it. But you have your entire family at risk, not a good plan at all.
Keep thinking, but think in terms of renting something (house) in your new area. Far cheaper and safer.