Had a thought about poop boards...
A friend of mine gave me a cage for my 2 older chickens. I didn't want to use a wire bottom and a piece of plywood would not fit through the door so I bought a couple of rubber bathtub mats (with the suction cups on the bottom) and put them on the bottom over the wire floor and then covered them with pine shavings. This can be done for poop boards too, without having to worry about trays sliding around. They can be easily rolled up, dumped out and hosed off for cleaning. Just a thought.