We are getting ready to do this same thing. We have decided the house goes on the market 11/20 and once it sells we are going to move into our current unit until we can get our full time unit built. Once that is done the current unit goes to a consigment lot and we will live in the new one until 1/2017 when my wife can retire. I will continue to work to build my pension until she can retire even though I could retire as of a year ago. Our plan has always been to full time so we just figured lets start now and not have to deal with the house and it's upkeep the next three years.