H.W.
Okay, here's the deal--- yes, a stall is fine, but learning to adjust is even better.
A few weeks ago, my son went off to Scout camp. He didn't want to shower in front of the other boys. He proposed a few different options (including not fully undressing, Ha!).... I told him "listen, everyone else is doing this too. You are going to get more attention by trying not to be naked than you are if you just get in there and take the shower." Worked!
I've been in groups of women (esp in boot camp) where one or two don't want to fully undress or something like that. Guess what? Those were the people who got the most attention because they weren't doing what was normal for the situation. I remember being self-conscious of my body at that age, but it doesn't help to not do it, or to be late coming out for the class. (and possibly marked tardy). So, I strongly suggest letting her get used to doing this, even if it's in a stall, but do NOT get her a doctor's note or even entertain the idea. It doesn't help her in the long run. I