Can you hang a towel or jacket over the corners of the truck bed to block the reverse and backup lights?
The center pin of your 7 blade connector is for reverse lights. You'll have to get a meter or test light to see if it's connected to anything though.
I want to add reverse lights at some time and will probably use some LED fog lights from Harbor Freight. I'm thinking I'll mount them in front of the trailer tires pointing back down the side of the coach. I really don't need that much light on the rear as I can't see back there anyway.