I don’t mean to be negative, but without changing the position of the roll hoop in that cage, I can’t see any seat getting you further back than in that picture.
From my understanding, you really want your head comfortably in front of the main roll hoop. The idea being if you are in a collision there’s no risk of your head contacting the bar, which would be the equivalent of being beaten over the head with an iron bar…
I know it’s drastic to start changing the cage, but if you want to get comfortable and safe at the same time, it might be needed.