I may also try following the section in David Hall's article where he shows how using RTV and plastic wrap on the lower rudder casting
I did this earlier in the season. I was able to get one of the rudders perfect the first time out and the other is still not working properly. Since I have to do a bottom job on one of the hulls now, I am planning a trying the RTV trick again. This time I think I am going to clean out all of the RTV, redrilling the rudder and than applying the RTV. Whereas I had applied the RTV and than Drilled the rudder before.