I guess I can see what you mean when you explain why you wouldn't want to go stealth. Still, it's high school, and teenagers can be pretty mean - trust me, I'd know. I'm still in high school, and I've got a year and a half to go, but currently, I am
known as a girl. Point being, if you don't know me... well, let's just say that I've gotten several strange looks and comments when walking out of the women's restrooms, so much so that I don't even use the restrooms at school anymore...
Long story short, though, my dad and I have decided that it's best if I change my name and speak with the school before the next year starts so that I could be registered as a boy and treated as a boy by my new teachers and classmates. It's such a big school that almost no one would notice, and the people who matter already know, so I guess I'm going "semi-stealth."

I'd say let the people closest to you know that "hey, you're a good friend of mine and I just thought you should know that I'm trans..." etc., if you really want to tell them, but otherwise it's probably best to keep it to yourself for now.