Straight to the rear glass - gotcha - just notch the light a little on the bottom to make room for the wires, right?

Careful Brian...I don't recommend notching glass if it is tempered. Notch light, perhaps.
Light is slightly flexible too.

Let me regroup and see how best to run wires.

I need to finish my V8 car first...but, I'm sure there is a simple solution.

In my case, I wanted a 3rd brake light you couldn't see during the day.

Oscar

Hey @ValcoOscar - correct. I wasn't talking about notching the glass, no. Perhaps the bottom of the light (or just removing a very small portion of the adhesive) - maybe. I just got mine and it's slick. Really small but really bright. I like the the running light option but I'm undecided if I'll hook up that part.

I'm thinking mounting on the bottom of the window up against the engine lid seal and then route the wiring under the seal and into the engine compartment and then to the tail light wiring.

Curious to see how you end up doing yours as I won't be able to get to mine for a while...if things continue as they are.

Also - just a firm rub with your thumb will remove the printing on the lens - then it's really clean.

That piece will fit into an opening cut into the upper chrome trim piece. It’s actually a 3rd brake light for a Ford FT, so not a bad ancestry.