How are going to use wedges in adjustable ( you mean SPLIT) boards?
Another way to avoid your problem is to use a board that is collapsible in the head area rather than butt. To avoid this use a head spacer that can be easily removed through the pelt mouth area. All that’s required is a standard clothes pin, a headless nail, some duct tape and a 6 or 8 inch sip tie. The spreader nail should be no more than 4 inches from the board tip to facilitate removal of the cloths pin spacer. Pull the spacer pin, squeeze the boards together and the pelt is removed very easily compared to the normal procedure with a collapsible board at the butt end.