Please review federal court decisions regarding this. Many of those restrictions are in fact illegal. Barbers Hill ISD is embroiled in a multi-year lawsuit from a kid because he has dreadlocks and the principal/superintendent refuses to let him attend class until he gets a haircut - in spite of many cases even up to the supreme court level allowing boys to have longer hair - and a Texas state law passed a few years back allowing ethnic or traditional hairstyles.

If your dress code says "Facial piercings are not recommended due to potential of damage to face/instrument" that's one thing, but outright bans may not be enforceable if your parents want to get litigious.