This is a very interesting conversation since DW and I are pretty much in the same position, but waiting for 4 years until the youngest is out of high school to begin full-timing. We decided to purchase a used Class A in May so we could see if this was REALLY what we wanted, only time will tell. I am in my early fifties and DW is in her mid forties, so for us to be able to full time in 4 years will require some workamping and savings and hopes that the house will appreciate in value during that time to be able to cover the mortgage as we are currently underwater on it.
I am not in any position to offer advice, but sure hope to learn from those that have been there and done that.