Another take:

Start with Luke in the cave (altered to look like Dagobah) finishing his lightsabre. No Vader, just him. Keep the lightsabre off to keep the reveal when he activates it at the Sarlaac pit. Cut to outside the tree (from a shot in EMPIRE), camera pans up to star field, slowly rotates 180%, and camera comes down to 3P0 and R2 approaching Jabba's palace.

This could add implication that there are other Siths after Luke (being that you can't tell too well if it is Luke under the hood) or Luke has been completing his training since the 3 to 5 years since EMPIRE ended, as well as his planning of rescuing Han as his "final" per se.

One of my biggest problems with JEDI is the editing and the pacing. There is really no need for Vader's scene in the beginning, as the Emperor arrives later and we once again see the Death Star 2. Vader is still introduced when he meets the Emperor, and you would be able to cut out one more Imperial shuttle landing. By starting the movie on Tatooine (or with the short Dagobah prologue), you jump right into the movie from where the characters were planning on going to at the end of EMPIRE, as well as essentially start the movie with the 2 robots that... well, started the first story. This also saves the DS2 reveal for after Jabba's story is completed