You're right, of course. Am I Autospeed's problem now?
I remember about the sills, but what impressed me was the tube buried in the bulkhead to locate the Hydrolastic suspension bags.
The rear suspension was used by Inrekor on their flat-pack Porsche Speedster chassis:
https://ecomodder.com/forum/showthre...tml#post533399
From 2011.
Inrekor is gone now, but they had an interesting product.