Motor homes are honestly not really family friendly. Not many have sleeping space for more than two adults. Add in two drive trains to maintain and it just is not the best solution for a family of four. Where are the kids going to sleep? Making up a couch or dinette for a night or two might be OK, but every night? Not practical in the lease. Are these teenagers the same sex? If not, therein is another major problem. You cant expect a boy and girl to sleep together can you?
Now full timing is a life style, NOT a way to live cheap. Add in the space rent, fuel, electricity and your right against the cost of a decent apartment in many places. Where are these teenagers going to go to school? Where are they going to do their homework? Where are they going to have private time? And everyone needs private time. Now, how about your job? You going to be parking in one place for months at a time? Not the best on a motor home.