You know until I read that post ^ I hadn't thought about the problems of the main crew being constantly refered to as Commander and General etc by the rest of the Rebels. Not such a problem with Lando since we see how his field-promotion comes about but without the Yavin Battle, medal ceremony or anything, taking Luke, Leia and Han as credible leaders is an issue.
btw not sure if this is a possibility, I'm just shooting from the hip here. Could the (Unused) battle of Yavin footage be used as an opener? Remove all shots of Luke and it could be a last ditch assault on the Death Star to buy Leia time to escape on the Tantive IV. Remember before Luke hits the sweetspot with the help of the Force there is a heck of a lot of missing and dying from the various Rebel pilots. It might just be possible to use the shot from ROTS where Vader and Palpatine are looking at a half finished DS to be a shot of them watching the battle from the bridge of the Stardestroyer that soon pusues Leia. This would nicely foreshadow the Emperor watching the Endor assault later on. Plus when cut with the Yavin footage it'd help sell the fact that the battle is taking place above the same half-finished DSII we are gonna see at the end.
If you completely swapped out the audio in this shot ^ you could have the Emperor saying anything (We don't see his lips I believe?) using borrowed dialogue from ROTS.
"We must move quickly. The Jedi are relentless. If they are not all destroyed, it will be civil war without end. First, I want you to go to the Jedi Temple. We will catch them off balance. Do what must be done, Lord Vader. Do not hesitate. Show no mercy. Only then will you be strong enough with the Dark Side to save Padmé"
^ There's probably lots of other dialogue options but that was the first that came to mind.
Also another thought. This ^ could be used to introduce the idea that Tarkin is the Captain of the Stardestroyer while Jerjerrod is the Moff. That's if there is footage of Peter Cushing you still wanted to use? Tarkin turns away at the end. Could it be because Vader just told him to "lay in a pursuit course"?