I mocked up the scene with the added shot as posted above, fully implementing it and doing audio in order to assess whether it really works that way.

I would say that I wouldn’t worry at all about catering to the viewer’s expectations for Mustafar, and just make sure that it’s consistent within this movie.

With that in mind, if we can only have two shots I’d lean toward the castle and the forest with TIEs. Either this new shot fits as a dramatic establishing shot before getting into the transition into the action or it feels too out of place. I think the timing of the music is slightly more favorable with just the two shots, also, but not to the point of precluding using it if it works.