If it was me, I would go to Home Depot, get a sheet of plexi glass or other clear plastic, 4 large pipe hold down clamps and make a pair. I have tools to cut and drill plastic.
You could try a Harley Shop as they make different models. Maybe look on eBay or Amazon. Some windshield companies also sell them as accessoried.
It has been raining so much her is CA that I have not gotten to ride much this winter. The last time I was out I noticed the same thing about the wind coming in from the side. Not a problem in summer but would be nice to minimize it during winter. If I make something I will write it up in detail on here.
Happy hunting.