This puts the light facing directly backwards with the plate on an angle. I attached an old plate to see where the fender might be cut and outlined it with black tape.
The plate would hang over just a bit of the fender.
Next I replaced the orange lens with red lens on one of the turn signals and in the process found that the turns have a running light in them. Very good. Extra light in the rear.
I tried a couple of locations.
I'm thinking of mounting the turns off the tail light using a tubular mount like on the front of the bike. This will take a bit more planning to find suitable tubing. More as I progress.
My plan is to NOT disable the existing lighting until I have the new lighting working, then I will remove the old, and THEN cut the fender. I want as little down time as possible during this build.