OP, you seem to be confident in wearing a bow tie. Go for it. Based on how you describe your current wardrobe you should be able to pull something like this off:

Some better fitting pants (denim or slacks doesn't matter) and smarter shoes and you will be all set. You can always take the tie off if it needs to come to that. I agree with the ideas that the tie should be the most formal part of the outfit and not the loudest either. At least at first while you get comfortable and nail the look. A madras tie can also be good once it starts to get warm and doesnt have to be overly loud.
Your styles and tastes will change so there is no harm in pushing it for one day. Dont let the haters get to you, here on this thread, forum or real life. Have fun in hs, enjoy yourself, and do well in school.
L