Actually, the center pin of your 7-pin is designated for back-up lights, but almost nobody uses it. Even if it were available all the way to your rear bumper, it wouldn't do you much good. Your flood lights would go off when you shifted into park to walk back and eyeball the situation. I would not run them off the running light circuit. My TV runs that circuit through a 10 amp fuse. We light a lot of lamps off of that circuit as it is, and two floodlights would blow that fuse. If you're going to mount them, and I like the idea, just put a waterproof switch in line and run the wire (fused) to the trailer battery. I'd mount the switch somewhere around the battery/propane tanks, so you don't have to walk all the way back.