I joined the rear fog light Blue/red wire white/black brake light wire using a push on joiner.

I then used a 25mm hole saw to cut a hole in the plastic where the light should go. Then used a sharp stanley knife to cut the knotches for the lugs on the light fitting.
I bought a light fitting and 2 male spade terminals from an auto elec for $10. I pulled the black wire out of the plug, cut off the spade terminal and joined the new black, along with the old one, crimped on a spade terminal then popped it back into the plug. A spade terminal was also fitted to the red wire and pushed into the plug

This is the view from the rear

And at night
