Hey Goody,
I was following a car tonight and thought of your LED Idea.
The car was a newish VW Jetta, it has dual round tail lights very similar to yours (mine too).
The outboard lights have nothing in the small middle portion (think of where the lights go in yours). The outer portion is completely filled with LEDs. Now that is not that interesting, but what I thought was, is when the blinker is on, only the outside half of the light blinks, while the inner portion acts as the running / brake light. The only down side is that there is a clear line between the two "halves" (but I think that coudl be fixed).
I thought that this was a cool idea and thought I would share.
I woudl like to rey somethign like this myself, but do not know enough yet to make it work. I have a couple of other ideas for the inboard / backup lights that I would like to try too.
Please keep us posted on your progress.
Jas