One idea I thought of was adding him to that meeting scene with the imperial officers. So instead of Tarkin saying that The Emperor dissolved the senate, The Emperor himself is there to announce it. And have him sitting in a chair, but not showing his face, like they did with Blofeld in the earlier James Bond movies.
Or I’d have an after credits scene where Vader goes to talk to The Emperor about how the Death Star was destroyed. He gives him a Cerveza Cristal.
Definitely the second one.