[folivier]

Mark please take plenty pictures of your install. I've been interested in mini splits for a while now and if/when my roof airs die I might consider replacing them with mini splits. This is on a Foretravel but the same principles would apply to a Newell. First you need room for the compressor unit then a place to mount the evaporators inside. The evaps should fit where the valence is by cutting out a section. The copper tubing & wiring run is already there for the existing split units on your coach, or through the ductwork on newer coaches with the SCS units.
I've been following a few who have made this conversion, mostly in 5th wheels, and they have all been very pleased with the better performance and lack of noise.
Good luck!