Rack on the truck bed, Yakima BedRock?

Has anyone used a bed rack (Maybe Yakima BedRock?), and then put a cargo box on it? Pics of it? I have a SkyBox 16, which may be too long for my 5 foot bed, and I want to keep it so the lady can also use it on her Subaru, so I want to see if it will fit on the back of my truck. There may be 1-1.5 ft of SkyBox overhang off the back of the truck.

I don't want to put a camper shell on it yet, otherwise I know I could put the box on a rack on top of the shell. I want to try and keep the utility of an open bed an easy option.

Thanks!