This might not be exactly what you're looking for, but something to consider maybe.
I coated the tub in monstaliner and removed carpet.
I recently got the epiphany to build a floor liner/mat that really fit what I needed. I wanted solid, cheap, and for it to add a small sense of "comfort" look to the bed liner. No homo, but it is nice to have comfort somewhere lol
So I built ^that. It is think enough to fit around the tie downs in the bed and basically eliminate them. Now dogs can lay back there. It's abrasive to what ever is on top of it, and it holds in place quite well on the floor. And it's soft, so luggage, valuable things, etc, can be laid on top of it without sliding around. It's easy to clean and remove. I was pretty proud of that project! It costed $0 because we had the stuff just lying around.
Now, due to fitment of the rear seat's boots, idk if it'd go well with a rubber mat on top of it because it would hinder the boots to go in the holes drilled in the plywood.
Just a cool idea I came up with! My bad if it wasn't really what you were looking for.