sorry, the one that shows up better when "off" is
http://www.baddad.com/instructions/install/4
no reason why this can't be applied to cars. I thought I should contribute.
Fine work you're doing ,just thought I'd toss in an option for rear lights that work for me, of course only if it's legal.
http://www.motorcyclemetal.com/downloads/How%20To%20Fabricate%20A%20Hidden%20Tail%20Light.pdf