Well my 7 year old grandson found it for me. I have been told that the "Happy Max" motorhome in the movie, RV really didn't exist, but we have located it in a museum in Amarillo, TX! We will be going through Amarillo tomorrow, July 12th and hope to stop and see it and others in this RV museum. I believe it is even a free museum, I will post updates soon.
It is a great museum, and the owner of the RV dealership and museum could not be nicer. Very nice historical RVs and motorcycles in there and it is all at no charge. Go see it when visiting the Amarillo area.