The new Rudder Skin arrived from Van's so I re-assembled the rudder components and set up the trailing edge for drilling again. I spent more time setting the rudder up on blocks such that the trailing edge was level and, because the Aluminum Angle was already drilled I was able to put a Cleco through every hole in the rudder skins and into the Aluminum Angle. The Cleco's went in easily, without binding. Based on this I have concluded that my original set-up was flawed and that if I had clamped one skin to the Aluminum Angle and drilled and Cleco'd all of the holes I probably would have avoided the problem I had with the skins in the first place.