You don't have to remove everything (just a lot).
To access the control, you need to remove the horizontal ledge above the tub (to the left).
To do this (at least on my Overlander which is probably similar), you have to remove two screws that hold the end of it to the bath/bedroom wall. (You also have to remove the trim strip from the aluminum channel above and below the ledge piece so you can remove the rivets which connect everthing together.
The biggest frustration is having to remove the bedroom wall (double wall with pocket door inside) in order to remove those two screws on the end of the ledge piece. The aluminum channel is no big deal, although the plastic trim insert will probably crack up when you remove it (old and tired).
We replaced all of the plastic trim insert with linoleum strips cut to size...looks much better now
Hopefully in your Sovereign
, you have a closet or something just forward of the tub and you'll have easy access to the screws. (And won't have to remove a wall.)
(If your bath is totally different from mine, than disregard all advice.