I saw something I didn't know existed, at Pic'npull in Richmond. A Volvo fold up, toward the roof, dog gate that comes down behind the rear seat. It meets the top of the reat seat when the sear is up. It was excellently designed, I was impressed. I don't know what they'd want for it but it's there now in a car that hasn't been there long.
If someone wants it I could get it I suppose, it appeared to bolt in to the roof inside some small panels where the seatbelts go on some models of wagon.