I used some of this stainless steel hardware cloth (#8 mesh)
The wires are very thick and strong. The holes are small enough to keep even tiny rocks etc out, but does not hinder airflow. (window screen is too fine and too weak)
You can cut it to fit over the oil cooler too.
The first year, I used 1 sticky sided weather stripping to run around the edges, so it doesn't touch the rad fins.
If it does it will wear a hole in them.
The second year I used plasti - dip (the stuff that you dip your tools into and it gives a rubber coating to the tool handle) for the edges.
I used the stock horn mounting bolts to hold the top and then slip ties to hold the bottom and sides to the rad, and fairing.
You can make it fit side to side touching the fairing, and nothing will get through on the sides.
Today was my last ride for the winter so I will take some pics of it on and post them, when I start tearing her down for maintenance in a couple of weeks.