Sure D.
This is the 18" length of C channel.
here's end of the "C" piece.
Here it is with the camera mounted.
Here's some in the car...
It was not an exacting science, as you can see from my handiwork bending the metal.
Also, I just rested it in place against the headrest posts instead of zip tying it in place for the pics. I'm sure you get the idea though.