if anyone has the time and inclination, here's a trick I tried courtesy of a fellow owner in Brisbane.
4 x M5 50mm screws, 8 x nuts to suit, 12 x washers, 4 lock nuts - all stainless steel. This enabled me to mount the screen 35mm out away from the brackets. The idea is that airflow underneath helps eliminate the buffeting above by equalizing pressure areas.
I can't prove that theory but I have found it a useful mod.
If it doesn't help, you've spent $10 AUD or international equivalent for stuff that will probably be useful one day.