I'm planning on turning one of the small expansion boxes into a place to put as much as possible between sessions to store the campaign state:

Must-have:

• Rebel play areas (bought class cards and items, earned rewards, Bounty tokens) - mini American x4
• Rebel allies - American
• Imperial play area (bought class and agenda cards, earned rewards, villains) - American, optional mini American too
• Agenda deck - American
• Active missions - American
• Side mission deck - American

Nice-to-have:

• Rebel hero cards (ease of access; allies could go in here too) - huge
• Item deck (to separate out sold/unused items) - mini American x 1-3
• Supply deck (ease of access) - mini American
• Story mission deck (ease of access) - American
• Unbought class cards (ease of access) - mini American x5
• Deployment decks (ease of access) - American x1-2
• Rebel/villain minis

Before I actually sit down and try to lay something out... is there anything I've not listed above that would be useful to track the campaign state?

I use a few small bags and a bigger bag to hold the large hero cards and the smaller bags. I have no idea what you're trying to do but it seems to have a lot of American in it.

I have no idea what you're trying to do but it seems to have a lot of American in it.

I can smell the freedom from here.

It's the size of the cards. Sleeves and similar accessories use those terms.

There's "Mini American", "Mini European", "Standard", "Standard American" and "Standard European" that I'm aware of. Most FFG games use "Mini American" and "Standard American".