I didn't like how the shelf attached to the headrests either. I built a wood frame out of thin plywood that sits on the back seat retainer brackets, and attached it to the Voltshelf with two hinges. The frame is held in place by being sandwiched between the rear bulkhead and the seats. At the same time one seat can be folded down while the shelf stays in place.My '17 had a Volt Shelf in it when I bought it used, with the front edge hanging from the rear seat headrests. A Mickey Mouse mounting system if ever I saw one, I honestly couldn't believe that was how it was supposed to be installed. I read up on it here and sure enough - That's how the seller intended it to be mounted. It had been hanging there long enough it was cutting grooves in the top of my leather seats!
There HAD to be a better way to hang this thing! I drilled new holes so I could use the cords that came with it to hang it from the hook fittings on either side, just behind the seatbacks. The front edge is an inch or two lower than hanging from the headrests, but when carrying cargo, it rides up and still works perfectly well . . . . and it no longer looks Mickey Mouse
When needing to have both seats folded down, the Voltshelf easily lifts out and can be set on top of the seat backs with the wood frame hanging down into the rear footwell.
I also attached a black rod to the underside of the shelf near the back, to eliminate sagging. In doing so, I could hide the rear lanyard ends inside the lightweight metal rod. The rod is finished off with nylon end caps.
This took some work, but I bought the shelf right after buying our 2018 and plan on keeping the car 8-10 years, so it was worth the effort. No doubt, your idea is infinitely simpler though.
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