Think you'll have to experiment. Unless you can get to the fundamentals of motorcycle aerodynamics with your slide rule and a passenger.
As an example, on a standard Honda Dominator, I always had a brilliant ride in the wind, right up to, if I remember correctly, 100mph at times.
True, the wind was strong, but I suppose I had enough arm and hand strength to hang on OK and enjoy the sensation.
But then I took a passenger. Nothing high speed, maybe 60mph max. And my passenger always had a nice smooth ride.
But me! Once over 50mph the wind would batter my head from side to side so powerfully I just had to let it happen. And slow down if it was so bad I couldn't see properly.
My passenger would ask, "why do you bounce your head side-to-side so much when we're on the open road? It seems a really strange thing to do!"
So to repeat, I think you just have to experiment. Probably with different screens, or no screen, as suggested.