I am 6'6"... standard screen...
Just put the bracket, so the top 2 holes, are "above" the clock cluster, and screw it on... then put the screen on the highest holes you can get (sorry... LOWEST holes, making the screen HIGHER) and screw it all together, with the plastic trim things on the screen...
I get minimal, if no buffetting... and I do serious amounts of mileage... at 70+...
But like it says above... it all depends on how you sit, where you sit, your lid, etc etc etc...
Just have a play, and get it right for you... but try my set up... it works for me... so it might work for you...