[Sven7]

It's also an EK. I don't know if the trunks swapped between generations.

You could always fab something up but it would probably look bad and work badly (no offense to your fabrication skills- thinking about this from a designer's perspective).

Have you thought about mounting trunk levers up by the top of the C pillars? Some trunk lids now lift up as they open to clear the compound curves. You'll see this on most recliner foot rests too. Basically it would be two levers of different sizes on each side. Instead of opening parallel as matching levers do, it would tilt to the front. The longer the levers, the higher up the thing lifts to clear the roof. You could add a small strut or spring to ease opening.

That way, the entire thing would lift up like a liftback and might actually close and seal right if you do it well. Or, you could hinge the Kammback separately. This would probably be easier to do. You could line the bottom end of the thing with rubber tubing to seal it and attach some simple elastic hooks on the back to secure it.