I am not sure if the rudder will be a push rod or a '"pull-pull" set up. I have the rails installed for the elevator servo already, these were glued to the sides before they were jointed, the rudder servo can go there if I need tail weight. I decided to add cable exits before covering this way where ever the servo ends up, the plane is ready. I drilled a 3/4" piece of scrap though about 5" with a 1/8" bit the long way. Once drilled, I cut the block at the proper angle to act a s drill guide. Then drilled with a 6" aviation length bit. I glued in short piece of Sullivan NyRod as an exit. AeroWorks planes use a similar set up. The plastic tub on steel cable is near fiction-less.