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Red Ghost I agree with that assessment. I also find it cost prohibitive as well. You could try this route:
http://www.fordraptorforum.com/f81/rear-facing-amber-cargo-light-48121/
Stay factory looking. Not sure how well they work but seems like a great solution for you.
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Fusco0520 that seems to be the million dollar question. There are many options out there in an attempt to solve this. The one you have does check the requirement, but ultimately doesn't function as well as advertised. You have a Gen II so magnets to either side of the 3rd brake light wont work, which is a good option for a Gen I. I certainly understand you not wanting to cut holes in your new truck like silentshooter did. Though that is a really great set up.
You could look into a set up like the link above. If I were you I would fab up some angle iron uprights between the cab and bed. Snoball is no crazy beat fest so I wouldn't worry about them making contact with the cab. Drilling through the front of the bed and attaching with some nuts and bolts. Add stiffeners and backing plates if necessary. Run temporary power through the rear slider and plug in to your various power sources. Or to an upfitter. It would be simple and non permanent. Keep them laying on the floor or behind your back seat and before the drivers meeting head out to the parking lot throw them on and be good to go for the weekend.
I am sure you have stake pockets too. It appears you have enough room with your bed cover to access them. Make some uprights with some 2x4's or smaller, with a cross member at roof height. Paint and attach lights there. Disassemble and keep in your bed and again morning of, go out and put together. Those may not be the sexiest option, but ultimately they will be functional. And that is what is most important. They are a safety requirement. As long as they aid in keeping your truck and the guy or gals truck behind you in one piece and all occupants going home the way the arrived that's what is important.