Critical length of pull is usually what is correct to get your eye in the right relative position relative to the gun, because with a shotgun your eye is the rear sight. I had a friend with the same problem you are having. He started out as a rifleman and could not get comfortable reaching out there. He eventually went to a semi auto. But, all that is for wingshooting.
You would have to do an awful lot of reducing the length of pull to move the fore end that far back.