Not all flags are known sadly, but https://wowdev.wiki/DB/CharSections#Flags
17 = playable | unknown
19 = playable | barbershop | unknown
So both should be available on character create.
I don’t know what the unknown flag 16 does, so you may want to try to toggle that. Other than that, setting 1 and 2, and unsetting 4, 8 and 32 should enable skins for all classes and make them changeable in barbershops.