Ziz said:

Alternate idea - instead of showing DSII at the end of Empire, just imply that that's where the fleet is headed after the Falcon escapes them at Bespin.

Falcon goes to hyperspace.
Vader pondering what just happened.

Vader (walking down the length of the bridge): "Admiral Piett, set your course for the Endor system."
Piett (as Vader crosses in front of him): "Yes, Lord Vader."

Fleet goes to hyperspace.
Continue with ending of film as it exists.

If the timing is right, you won't even have to worry about lip sync. With Vader, it's just a matter of pacing for how fast he walks vs how fast the line is, and with Piett, it's a short enough line that he should be able to get it off during that second or so that Vader's cape blocks our view of him.

We don't need to see DSII. For the people who know what happens at the opening of Jedi, this scene is an easter egg. For people who don't know (kids of the future), it will give them something to reference back to when they do see Jedi... "Ah, so THAT'S why the fleet went to Endor at the end of Empire!"

This way, the implication is that DSII has been under construction for a while and going there is just a matter of "getting on with business".

Not a bad idea, but how are we going to get James Earl Jones and Kenneth Colley to film this for us? ;-)

I know what you're describing, but I think that scene ends best when Piett is just waiting to be choked and Vader just walks right past him silently.