When I built my RV-9A, I used the space between the lower hinge brackets as my exit point for the strobe cable and the tail light wires. Look closely in the photo and you can see the gray strobe cable and both tail light wires. The cable and the tail light wires later got a sprial wrap around them to protect them from chafing with rudder movement.
The exit hole in the aft bulkhead is adjacent to the rod-end bearing when the rudder is attached. The gray strobe cable is barely visible in this photo due to the poor lighting from my camera flash. The crimp ring was grounded later under one of the bolts seen here. I kept the strobe cable separated from the low-voltage tail light wires all the way back in the fuselage until they exit to the rudder at this point.
The cable bends down after it clears the steel angles that secure the rod-end bearing from the rudder. It flexes in the vertical axis as it dives down toward the bottom of the lower rudder cap. I did not cut away any additional fiberglass from the lower cap.
The plugs for the tail light assembly are in the lower rudder cap which is held on to the rudder with #4 flat head screws and nut plates.