The idea is that visibility should not be restricted. I don’t have the law in front of me, maybe Dustbunny has, but I believe the rule is that an object should not cover 20% of the window (teabag wouldn’t do that!)
In any case, no cop in PA is going to stop you because there’s a teabag hanging off your rvm. Other stupid reasons, sure, but not that one.
They are actually very reasonable here...YMMV!
If a cop wants to stop you, he will find a reason. Something hanging from the mirror would serve that purpose quite well.
If that dangler happens to make a political statement that the cop doesn’t agree with, especially now that DHS has branded all of us as subversives, a tea bag would be a perfect excuse.