CenterIsl: You have one of the best cockpit covers ever made by Porsche...it is called an electric convertible top!
No, I am not being flip, but after owning a 356 Cab and a 968 Cab for many years, I like you and the Bimmer cockpit cover, I found that to be just the ticket for not having to unbutton a bunch of tenax fasteners, pull off the tonneau cover and put the top up.
Now with the Boxster, I am in heaven. Sprinkle of rain, up goes the top. Stopping for lunch, up with the top. 15 seconds vs. a two man top and tonneau hassle, even tho the gray "shorty" cover you mentioned was great...unless it rained.
I also have the Porsche folding sunscreen. Got it on ebay.