Alex,
I have not been on here for a bit and just saw the thread. I made one from some plastic sheet from B & Q as a trial. I fitted it onto a Spyder roll bar with Velcro straps. It worked well in general and stopped all that air around your neck that makes you neck stiff the next day.
However, the wind found new places to get into us. This was around the arse region. The difference was that the pressure had increased and I got a savage velocity around my lower back and bum region. Then had a rug around my behind. In the end I gave up and took it out. I settled for keeping my window down, a bit, and blasting the wife. The window down tends to help. Call me an old tart, but I wore a hat (she did to) and had my fleece collar up. Even when the sun was cracking the flags.
To be honest, I think some people are more susceptible to drafts. Even the tough wife got a bad neck by going bare necked in 27 degrees C. She had laughed at me. I am talking about proper days out, runs of over 200 miles plus. Not around the block and back.
My DHC Elan has gone now and it did spoil the enjoyment. I don’t know whether the actual roll bar helped mess up the air flow and make it worse. I never drove it without a roll bar.
Mike

Another Northern softie ex pit man too, the shame!