For your backup lights, why not get one of those premade leds on a board with the wiring adapted to fit the socket? Plug it in like stock, hot glue or epoxy the board in place and blow away any pnp bulb.. Im spacing on the name, but someone made their own round fog lightd and made a thread about it..
Then you could sell what you have and recoupe some coin..
Seems like an aweful lot of work for what your doing..
I'm guilty of making little things into a serious project tho.. So I can't break your balls too hard