Soft ducktail held up really well. Only a little bit of water got past it when it rained going through Dallas...but at least I could see out the back without a lot of raindrops on the back window.
The duckatail does puff up as I was driving since the rubber coating cooled it in that position..kinda like what convertible tops do driving down the road. I was thinking of making a slide out version next...although it would take more engineering than I have at the moment.
. Maybe the ducktail housing could be sort of a roof heat shield, too!