There is no need to rotate tires unless you are experiencing an unequal wear problem. If I had a unusual wear issue with the front tires and felt I needed to get them off the front, I would move swap them with the two on the tag and leave the rear duals alone. There is no really good way to put just two tires on a set of four duals.
Former owner of 2004 American Tradition and several other RVs
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC