Are you going to use RTT illumination while driving?Nice. One thing though...
A lot of LEDs will have short life if subjected to much over 12v, so the ones designed for automotive use (13v up to 14.4v) will usually have a resistor to limit current.
If you have problems with short life on LEDs, you might want to try a voltage regulator mod like this:
(don't forget the heat sink)