I THOUGHT about adding a third brake light. It LOOKED simple. Just take off the painted fiberglass trim above the rear window and either replace the whole trim piece with the light or just bore a coupla holes in the old trim piece and add the light.
NOPE! That trim piece is ON there! I don't think dynamite would remove it! In fact I had the car painted before I replaced the back glass. I just planned on trading out the aforementioned trim piece. But I really don't think it can be done without breaking the rear glass.