Funny thing, I was at a local upholsterer day before yesterday looking for sheath making supplies, and unfortunately found several things I need to buy....
Among them their own model bed roll / bivvy bag which they can make to accommodate my size.
It will be quite expensive, and due to size & weight definitely for car camping only, but for sure something missing from my kit for a long time......
I was looking into getting one made several years ago, but got diverted by the hammock thing. Fully kitted on hammocks, bad roll next!