Appreciate the input and the confirmation that I need something to prevent camper/ rear window contact in my 6 3/4" box F 350.
B&W needs to call the OEM series something other than "Companion" because it leads to a lot of confusion. The OEM series combines a Companion coupler with a OEM puck style base that has four attachment points.
I confirmed with them that while the use of a sidewinder style hitch is verböten with their famous single attachment point Companion hitch that mounts to their Turnoverball underbed rail system, it "works just fine" with the OEM puck style Companion hitches and the rail mounted Patriot series hitches.
They discuss the issue here on their website. Keep Wedges Out of Your Companion Fifth-Wheel Hitch
I considered several solutions to the short-bed issue. Replacing the truck with an eight foot bed version was a possibility, but my truck is fairly new and I am not ready to replace it for another two years or so.
I considered a manual slider, but the numerous stories of folks mistakenly thinking it would be ok "just this time," ruled out that option for me. The auto sliders are nifty, but look to be a bear to get out of the truck. I was also concerned about clearance between the rear and bottom of the pinbox and the sides and tailgate of my truck bed when in the extended position. I am already wary of that even without the slider due to the height of my truck in relation to the height of the camper designed for a 1/2 ton truck.
I seriously considered the Andersen hitch, and may ultimately give it a shot. I am a bit worried about how the system will tow without the 5th-wheel plate stabilizing it. My friend has a camper with a goose-neck adapter and it behaves strangely at times.
So, I ultimately decided to go with a standard hitch and a sidewinder style pinbox. I am impressed with the Companion coupler so I went with that hitch. I was tempted to get a rail adapter for my OEM underbed rails as this would give me several more options for hitches, but I ultimately decided to keep it simple.