I'm all for the double throw switch with center off. For years, I've wired driving and fog lights that way. I have "ON-OFF-AUTO" modes. Driving lights pick up automatically with high beams, fogs with low beams. I should have used that scheme for back up lights, but I was lazy last time.
Getting a light that plugs into the trailer socket is good. But now that it's mentioned, I don't think I want one that adds load to my backup light circuit. It would be handy, though, to have a little mag base working flood
that ran off the "hot" trailer lead.
Hmmm... I could make up a compact, powerful flood that incorporated a relay and used the 7-pin trailer plug, for power, ground and control by the backup lead. It could mount in the receiver, and would be great when I wasn't using the trailer.
Those lights in the back bumper of that Dodge look nice. I have all the lower rear lights on my horribly ugly 1966 International 1300 4x4 "offroad" truck protected by, and shining through holes in, a a 6" channel iron bumper. My installation isn't so nice looking, but we both have the same idea. We do tend to bump those rear lights when working our trucks in the field.
I put a rear flood on my Yamnar, since it only came with a small pair of headlights (and turn signals on the fenders). I'm using a lead that switches off when the key is off. It's easy to forget a light if you shut down when it's not dark.
My trailer has backup lights both to the rear, and shining outboard and back from the back side of the fenders. I like light to the side. Years ago, I bought a 1978 Saab 99 Turbo. It had backup lights on the back corners of the FRONT turn/park/cornering light pods. It was nice to have light alongside the vehicle with backing up or parallel parking.
Here in the wet, shady, brushy Pacific Northwest, you can't have too much light.
