Chasing this cooling issue for months

TrailBeast;
A 195* degree thermostat should maintain an average engine temp of 175* with a good cooling and air circulating system. Remember that it isn't like a light switch on/off. You have a bypass hose and most likely a bypass built into the T~stat as well. 195* is the full open temperature but that stat will partially open at 175* try one in a pan of water and watch it. That partially opened position with highway speed airflow should give you the 175* operating temp you are experiencing. It is this exact same reason that I used to recommend to my diesel customers to run a 203* t~stat to maintain a 190* engine temp. Since the 195* is the highest I know of for your car all you can do is install a system that blocks airflow through the radiator at speed. The louvers you mentioned with an electric motor controlled with the same type of thermostat as your fan should do the trick.
~Michael