Hairstyles for girls that'll make it look short under a hat

Hi so I'm student directing in a show and the costume people are insistent that the girls playing ensemble guys do their hair in a way that it looks "era appropriate" under a hat. This wouldn't be a problem if they weren't PULLING PEOPLE OFF STAGE because their hair is too obviously not short. We open tomorrow and I'm probably going to end up doing a lot of hair. I will probably do slicked back buns for now but if anyone has any other suggestions, that'd be awesome. If it helps, everyone is wearing fedoras.