Well, I'm just back from the test flight.
All is well. It definitely reduces draft between the seats. There's a bit of shaking, but then the whole car shakes, so it's not obtrusive. It stayed in place and didn't try to drop back.
There were two unexpected outcomes. First, with a low winter sun, there is a lot of reflection, and it was flickering on the car in front and probably dazzling oncoming cars. Maybe I should look at tinting. The other thing is that the top of the perspex appears as a horizontal line across the middle of the rear view mirror, so the bottom half is partially obscured by reflections.
If I could get a satisfactory finish on the bracketry, it would be 'marketable'. But not as it is.......
