Started final routing of tail light/strobe wires. Drilled holes in lower area of aft two bulkheads before the very last bulkhead (F-710 & F-711), then noticed the tail tiedown bar F-712E blocks the lower area I wanted to run the wires into the fiberglass rudder tip. So made part F-712E (cut to shape, drilled rivet holes) removed assy F-712 bulkhead, match-drilled rivet holes, and cleaned, Alumipreped, and Alodined F-712E and F-712. Next: rivet F-712E to F712, continue routing wires.