Sharpest Tongue in the West
you could probably do some kind of retro fit for some rear low level lights in the rear of the centre armrest, easy to hide the cables, easy to find power too. Personally I wouldn't bother though, as there isn't enough space in the back of an A3 to see your feet even with the lights on!
There is a thread on here if you do a search for installing all the LED lights under the dash and doors etc, good luck with it, I dont think it's a simple job, but a nice upgrade if you do it.
2006 Porsche Cayman S |1988 Ford Fiesta XR2