I’m very new to the site so apologies if my suggestions for possible extras is wrong, but thought of the following:

Adding the two ewok adventures to ROTJ as extras.

Also there has been a recent doc on the bbc iplayer “Star wars at the bbc” which has some interesting segments related to the promotion of the original films including an interview where due to a strike the show was disrupted by loud music being played outside the studio.

Good luck with your project.

Regards
Jay