I hope you realize how incredibly *common* this is. When I was 9, my brother and I went to an in-home daycare over the summer. There was a little girl there, 2 or 3 years old, who would totally strip to use the potty, and sometimes she'd strip for no reason at all.
My son is 13 months old, and he has been known to take his pants and diapers off. Also, the only shoes that stay on his feet are Robeez because he can't pull them off. He pulls other shoes off, as well as socks.
Advice? I don't know if I have any, except keep your sense of humor.... Let her teachers at school know that she is going through this phase--she won't be the first they've seen, nor the last. Also, let your daughter know that at home when she is using the potty or taking a bath she can undress, otherwise she has to keep her clothes on. Try to keep it shame-free so she doesn't have issues later on (LOL). Modesty can and will come later.