The only thing I can say is WOW!!
You did exactly what I would have done and that is to source everything. No cutting or splicing or hack-job.
One suggestion: get yourself a red LED bulb: http://www.v-leds.com/Exterior-LED/B...10367-1-2.html
Trust me, get one. I have experience with OEM and aftermarket rear LED lamps that are relatively small like the OEM one you have and an incandescent bulb will get hot and tend to melt the housing. An LED bulb produces almost no appreciable heat and so you can expect to avoid the possibility for any melting to occur.