I thought student evals were just a way to make the students think admin. cares what they think. But, having been a teacher myself, I know admin. will use any excuse it can to harass you if you are not one of their favored ones. And with tenure being mostly a thing of the past, you are even more vulnerable. Have you & any of your colleagues considered organizing a NEA local? In spite of SC's right-to-get-screwed laws, a union can be very helpful if litigation is required.