Yeah, the ignorant little buggers can display the flags in their pickups, because those are personal vehicles. The T-shirts are a different thing, and the school may be able to prohibit them. Would they allow Nazi flag T-shirts?

to be able to regulate displays on vehicles parked on school property

Including sports T's and the like.

Easiest way to go.

..were forced to hang-out with idiots.

... swastikas on campus

and guess what happens?

When I was going to Jr Hi School in Detroit (1951), there was a fad of Civil War kepis (the soldier hat) for all of the boys. the hillbilly kids whose families had moved up the Detroit from KY and TN wore the gray ones while the children of European immigrants wore the blue ones (most of their families came to the US post-Civil War). It lasted almost a year and was a fashion statement with few fights as I recall (me, I wore a replica of MacArthur's WWII hat with the gold braid).

when I was a teenager?

News 2 contacted Rutherford County Schools spokesperson James Evans who said students have the right to express their beliefs under the First Amendment.

He said “As a school district, we can’t prohibit such items unless it is causing a disturbance at school.”

and there were many such efforts in that time and place, mostly intended (it seemed) to silence liberals

So (of course) my friends and I practiced the art of non-compliance and made ourselves the biggest pains in the ass to officials that we could, given our limited experiences and resources

something about young and foolish then and old and foolish now

I once had a teacher tell me to turn my Dead Kennedys "Nazi Punks Fuck Off" t-shirt inside out. I flatly refused, and I was almost certainly - in the time-honored fashion of teen boys - kind of an asshole about it.

I was sent to the principle, who totally sided with me. I liked discovering some people in power felt as I did.

Let the little hillbillies wear their flag shirts. They don't have much of a future anyway.