Shamelessly nicked from Stromtrooper, I thought it seemed a good idea.
Basically using the rear number plate light to also light up the rear reflector, essentially giving a second rear light but without extra wiring or adding extra lights.
Trim the inner part of the light housing WITHOUT drilling into the reflector. I chain drilled, I'm sure a dremel etc would do the job.
I also added some silver tape left over from doing the indicators to hopefully throw a bit more light.
And fitted, one with, one without flash.
On two occasions I've had a failed rear bulb at night & it's a scary experience, hopefully this will serve as a back up.
I'm not sure of the legality of this as the reflector is essentially now a light so I'll buy another self adhesive reflector for the rear.
BTW, those exposed nuts for the rear light look a prime candidate for siezing up, they are now well lubed & protected from the elements.