I'm guessing a category for every mainline campaign and their difficulty levels?

Yep, that was the plan. If there's a UMC with sufficient interest (at least 2 runners) I'd also consider adding it.

I honestly didn't expect this to get approved so quickly, so I'm a bit behind in preparing the set up. Should be ready in a few days.

So I guess the dev version is allowed? I heard Under the Burning Suns was changed a lot between stable and dev versions.

Unless players feel very strongly that a particular version should be disallowed, I'm inclined to keep it open to all versions.