It's the same as the folding floor in my 2015 1500, near as I can tell. I've had more 400 lbs loaded on that floor on a number of occasions, no damage. It was in large boxes that were spread out. A piece of wood like you described would be good.
That truck is 5 years old now, and on the driver side, the fabric on top is starting to come apart from the internal material, whatever that is. That's because I let the dog ride on that floor. He runs up and leaps in, and he hits hard, weighs 60 lbs. That lets the front piece of flooring drop a half inch or so if you put weight along the hinge. I've considered putting a replacement hinge like a piano hinge on it. To do it right the hinge would have to be on top, which would make sliding gear and boxes in and out a lot harder. I've been thinking about taking the flooring off, and replacing it with the same pattern in 1/4 inch or 3/8 plywood. Keep the feet, or make replacements, would be easy to do either one.