I was lucky enough that my parents had engaged with the school system overriding my (and my siblings) civil rights in the past. A little bit of push-back from them quashed a lot of school bullshit. As long as I wasn't endangering myself or my class, and not disrupting the education of other students, I had carte blanche to do what I wanted.

When the whole "trapper keepers only" thing went down around 8th grade, I kept using my backpack, since I walked a little over a mile home from school every day, and the trapper was dead-weight.