Doug,
1. Not sure I understand the problem. Am I correct in thinking that the ‘yoke’ is gouging the woodwrk on the for’d side of the aft cabin bulkhead? In which case what happened to the metal flange and sleeve arrangement bolted through the bulkhead? Have you a picture?
2. Suggest nipping up the bolt at the foot of the whipstaff so that the whipstaff can’t flop forward. Makes it rigid of course, but will solve the problem. If you don’t want to do this, then a light line made fast at either end of the horse and dropped over the fore side of the whipstaff ought to prevent it flopping forward. Not too tight a line though.
Aye Mike