I'm pretty sure that you would prefer to keep your books separated but reading the test pdf immediately made me think about a tiny expansion to the race building rules. In fact that would be the best place for some of the mythic flaws like material weakness. Having race point cost for those and for a very low-powered mythic ability (one daily use of mythic power to add 1d6 to a d20 roll, converts to an additional daily use of mythic power if the character actually gains mythic tiers) would be great.