Disabling some, but not all, EA skin tones for random?

The skintone update was good in theory but like most things EA does it was horribly botched in practice: I'm sick to death of having to go in and change randomized townies who spawned with the spray-tan orange or sickly purple skintones the game seems to love so much. I don't want to disable and replace the entire set of skintones, but I DO want to stop it from using the worst ones for random. Since skin tones don't appear in the CAS part browser to make an override, though, where do I find them?