What a great idea. I have seen a multi rooster approach work best in a very large flock. Not sure how big yours is, but you never know what they'll do till they do it.
I think you are right, the big obvious combs are cockerels, the small colorless combs are pullets. There were a few that had small combs with a little color. Those are the tricky ones, since it could be a slow developing cockerel or a fast developing pullet, so maybe some updated pictures in a...