Well, I went to OSH and checked out their selection of double sided tape and...well, Scotch's "5 pound" (they have a 20 pound) double side tape is apparently strong enough to resist prying with a flathead screwdriver, except it is also essentially non-removable. I don't think I want to mess with the fabric anymore. I thought about attaching something to the rear window, but there's no way I can fit something big enough and have the top still fold.
I guess I'll just give it a spoiler, then modify the rear belly pan (and do wheel fairings if I still have time) and then not bother with it anymore. Somewhere down the road if I see an exceptionally good deal on lowering springs I might grab some, most kits lower the rear less than the front, so that should help with the softtop's sucky shape by giving the car some "rake".
It will sure be hard to get over the ugly 27 degree angle on the top though
