Thanks for the comments.

The guy in the video below used a mesh sunscreen to do the job, but installed it as a way of reducing turbulence in the front seat.

bmw wind screen

I may try something similar, but again, life in the front is awesome - it's the back seat where you feel like you're in a wind tunnel.

My vert has the fold-down rear seat option, so it should be fairly easy to rig something up. If I have any success at all, I'll report back...