Nice... Glad you decided to try it. Good luck with locating all of the parts to do it. In the MH's I've driven all where 2003 and Newer, 40' with either cummins or cat motors and the allision tranny. They had the shifter you are talking about. It appears to be all electrical and I have seen them mounted on the arm rest, on the dash to the left AND right of the steering wheel. One had it in the center console area which was still reachable by the driver. They seem to be fairly flexible for mounting.
You may want to look in a MH junkyard to get the tranny and controller you need?
I look forward to updates!