Yep, sounds like we have a near-identical setup! My temp switch is nominally 195 but it's in the middle of the top hose (and the gauge is in the usual WP hole).
So it kicks in at 198 and brings temps down to 192 before it shuts off. On the highway on a hot day, though, it only comes down to 194 and won't shut off. Which is why I started this whole flail and didn't just leave well enough alone

I have ordered an Autocoolguy PWM controller, pricey but has a great reputation in reviews. Just didn't feel like spending the hours on the bench to make my own. It will definitely work better than the simple full-on or full-off relay I rigged up.

What pulleys are you using to get "somewhat" overdriven? The stock a/c pulley setup is either 1.3 or 1.4 depending on year, model, etc.
I would like to try 1.1 or 1.2 but I don't think such pulleys exist.