May I suggest you cut all of the Emperor’s scenes before the confrontation? Neither of the scenes add anything besides the Enperor bossing Vader around (which sort of diminishes his character). With constant allusions to the Emperor (Moff being scared, Yoda’s warning) there would be a lot more tension when Luke meets him if we haven’t either. It would let the audience build him up throughout the movie.
That is an interesting idea. My only question is how to get him on board the Death Star without revealing him. Perhaps wipe to new scene while he descends the ramp of his shuttle so we only get a brief glimpse of him with his face obscured.