I took the overlayed pic and figured that it is 5inches from the top of the spoiler to the bottom of the kammback.
I have a small lip spoiler on the top of the window. I can use that as the anchor point for the top.
I'm thinking of using some polycarb and using a heat gun to curve the corners. Then fit the edges of the polycarb with some foam so that the kammback seals to the body.
I would probably build an aluminuum L bar frame that would have holes in it to hook small bungee straps to.
That way I could use the trunk and easily set the kammback on and off
