“Evidently there’s a “no advertizing” rule.”
Political speech is not advertising. It is, however, a God-given right.
In New Hampshire, in the Towns anyway, get 10 signatures on a petition and put it on the Town Warrant, fire the cops or cut their budget. Police powers are delegated from the people, it happens up here. The further government gets from the people the less control you have.
Not on private property, it isn't. Get on my porch with a larouche-sign, and you'll earn a lesson in rock-salt ;).