What about individual levels, for example: Mexico: 5 stars, or something like Japan: 3 stars? No upgrades would be allowed, as the point at which the player could come across the run would be varied, making it harder to get the right combinations. The same goes for weapon packs and the like. (cosmetics would be allowed)

I dig the idea of this. If you could dm me or post on this forum a potential rule set and list of ILs, I'll certainly look into that.