You might avoid saying "confront" as it's the sort of word that gets peoples' backs up. Try instead, "I am aware that the kilt is a garment that is not widely understood, so instead of just showing up in kilt and hoping for the best, I wished to discuss it with the school administration in advance."

Also, in your second paragraph, you might try making your lead sentence something like "When I brought up this issue with the administration, I felt as if I were dismissed out of hand, as though I had proposed something dumb or silly," which eliminates the possible reading that you thought you were doing something dumb in even asking.

Remember that your purpose here is to persuade, not to confront.