[COcyclist]

Your design looks like the Kammback profile I want to add over the hatch of my TDI Golf. As for vents and dew, in my experience dew and frost mostly settles downward onto the car. I am guessing that covering the back glass from above will prevent dew from forming most of the time. Last week I had 2 cars parked outside, one under canvas carport with no sides and one right behind it but not sheltered. On a cold, humid night the one under the shelter had clear windows but I had to scrape and scrape the other.

I can't wait to see how this progresses.