Well I have a 2015 Salibel and the shower plate and faucets are all one piece. Here is a link to a replacement for the type that I have.
https://www.etrailer.com/RV-Bathroom...77-000025.html As you can see this is all one piece and you have to be able to access the rear of the wall to be able to change this part. I supose you may be able to get to the rear of the shower by removing the back wall of the closet just to the right when you enter the unit, but I have never tried to do this.