Assuming you're going for something after Natasha and others returned to the Clan, I'd lean towards the black and red. Unless there is a canon source to contradict that, I think NK's cult of personality would gain traction pretty quickly within the cluster. The scheme went with her and her Black Widows, so it would be reasonable to go that route. Prior to her return, Alpha, basic grey, or any appropriate camo would be acceptable canon options.
I don't have Invading Clans handy to check, and in most cases the FMs didn't go below Galaxy/Regiment for distinctions to schemes, making the 13th an exception already. I wouldn't worry about it applying only to the command star. Again, unless there's a source that specifically says that, you can assume a uniform scheme across the cluster.