Flashbacks are valid. I’d probably rather go with bookending a whole episode rather than finding reference elements to flash back from (since that’s quite radical for Star Wars). But I think I’ll get my teeth in to the edit, and properly load the content into my brain, then see what options that gives us.
That seems like a good compromise. The tricky thing about doing a flashback-“Hevy” episode (couldn’t resist) is that it can easily send the episode’s pacing to hell if you’re not careful. I think the important scenes to include would be one of the Hevy/99 scenes - they’re the emotional core of the episode, and we should set up for 99’s turn in ARC Troopers - and at least one scene to set up Fives and Echo - our main Clones going forward in the series. It’s definitely going to be a trickier episode to edit, but I’m sure you’ll do a fantastic job with it, however you structure it!
That being said, I wouldn’t worry too much about doing things that are “radical for Star Wars,” especially if you only experiment with it in one episode of the series. It’s also pretty radical to have a 3D animated Star Wars show, or an arc built entirely on a group of droids being led by a frog. The important thing is what will best serve the story you’re telling! (And that being said, if you think the best route is to stick with a more “typical” Star Wars structure, that’s valid too!)