I do remember that General Mills did offer as a send away off of cereal boxes, a Star Wars tumbler, but I don't know if they ran a commercial for it or not. If they did, it was probably piggy backed with thier regular commercials for the stickers, cards and posters that were in their cereals.
Have you thought to try and track down any TV promos for the Holiday Special? I'm sure there were some. Those would be a hoot to see after all these years.
I'm sure that you are aware that there are DVDs out there with several of the vintage Kenner commercials. I checked your list and there were commericals for the Millenium Falcon, X-Wing and Tie Fighter from 79 and 79. The footage for the X-Wing and Tie Fighter commercial was first seen in the Star Wars collection commercial that ran during the Holiday Special. The entire X-Wing and Tie Fighter commercial did run by itself later.
There was also a commercial for the Star Wars Early Bird pack. Part of the commercial was shown in the Empire of Dreams documentary and I do recall seeing the commercial several times on TV in 78.
I seem to recall seeing a commerical for the first Kenner lightsabers with the inflatable blades. Boy those were really hokey. In fact, I'd almost bet that there was a commericial for everything that Kenner had at the time. I hope that you can turn up more Kenner commercials for Return of the Jedi toys. I only have a couple on my DVD. I have tons of Empire Strikes Back toy commericials but I'd like to have more from Star Wars and Jedi. The Escape From Death Star, Destroy The Death Star and Adventures of R2-D2 games commericals come to mind. I did see commercials for all of those games. Boy, the more I think about it, the more seems to come back to me.
By the way, I think that this is a great project. It will be interesting to see how much footage you are able to find. Best of luck to you. I can't wait to see the results. If I think of anything else, I'll post it here.