This is how he did it! Thanks, Jeff!
from 2ply...The window is a medium weight clear vinyl from the fabric shop. Cut to the size you want the window to be. Used a strip of nylon folded over and sewn with a zig zag to allow for stretch on the weather shield on the Clark. Next cut the weather shield material on 3 sides if you want a roll up cover, if not, cut off all 4. Sewed Velcro tabs onto the sides so it would hold in place, and a tab on the back so it would stay together when rolled up. Next I tape sealed the edges of the material to keep it from unravelling. I was just going to put 2 smaller windows on first, but decided a nice large window was the way to go!
It was easier to make than we thought it would be. The total cost of supplies was less than $10.00.