After inspecting tires, checking tire pressure, checking / tightening the bearing nuts I was unable to eliminate the instability. It was very consistent with the fairing installed starting around 80MPH and getting much worse around 85MPH. I ended up removing the fairing and going back to the stock windshield. It's disappointing, but I would rather have a bike that is stable at 85MPH with no fairing than have one that literally feels like it could throw me off.
There were some serious quality control, design, fitment and installation issues with the fairing that I will post about later. I'm in the process of trying to obtain a refund at this time.
I agree that the laid back style of the Hoppe fairing may lead to improved stability vs. the Tsukayu which has its windshield almost completely vertical.