A fix I am using is simply cutting felt paper to the size of the opening. Then put a 1 inch by 1 inch piece of hook, from hook and loop (Velcro), hook side stuck to felt paper at the forward edge of the felt paper. Remove sticky side from hook, slide the hole piece into position. Push up ( I used a screwdriver to stick hook piece to windshield) when it is under the black window edge so its not seen. It will pull off when you want, wont slide off from spirited driving (Maybe the ZL1 guys will need 2 pieces of velcro
).
I used black because it was sitting around the garage, but it looks like a dark grey would match better. Its easy to trim and get it to look good, and cheap when you make mistakes. It looks somewhat factory to me. I took a picture but cant post it. Hope this helps