I went to one of the top girls private schools in my state and I was definately the boundary pusher of my year....makeup, nose stud, crazy coloured hair, the lot.
My principal would have a go at me everyday and I would never change any of it, til it got to the point of her saying "ill rip that nose stud out of your face" to which I complained to student council and she had to apologise... LOL
But IMHO, if shed given up on harassing me I probably would've toned down the hair and makeup and gotten over the nose stud a lot sooner...they had a lot of double standards, like girls with dark hair could dye their hair bimbo blonde but a girl with blonde hair got in trouble for doing hers black... WTF?!
Sorry this doesn't help much just sharing my experiences, I think its great that most public schools let kids wear what they want, as long as its not directly offensive e.g. Anti religious slogans or swear words...remembering our kids go to school for education not a fashion show, I know I sure did a lot more asserting than learning!!