Actually I was just thinking about it and I could probably rewire my current brake light and make it a brake light and turn signal.
There are two bulbs in there that are two intensities. I could ad a relay and make the left or right bulb blink for the turn signals.
With that undertail, and the stock light. I think it would look really smooth. and if I needed to add another turn signal I have seen people add leds to their rear passenger pegs