I'm considering a tonneau for my Boxster. Does anyone have experience with them? How hard are they to install. There appear to be clips that have to be installed on the dash for the front of the tonneau to attach to. How does it attach at the rear? How hard is it to put on and take off? Is it more trouble than it's worth? Since I generally only drive it on top down days it seems a practical option. I always enjoyed the one that I had on my old Austin-Healey 3000.