I found an amazing video where hairstylist Janet Stephens recreates the hairstyle of the Vestal Virgins. She recreates a lot of historical hairstyles, which you can see at her YouTube channel here. They're fantastic!
Her research shows that vestals did their hair completely differently from what I thought. I had read ancient texts that weren't incredibly thorough, whereas she analyzed statues. I have never seen a statue of a vestal in person, and no one ever takes photographs of the back of a statue's head, so I was at a distinct disadvantage.
I guess I'll have to go back and change a few things!
It's great that people are still making new discoveries about the Vestal Virgins. I just hope they stop after my book gets published. Perhaps that's not a very noble wish.