I have created a kitchen area for my ducks. I used an old gate frame (2x4's) that had lattice over it and covered it with chicken wire too. I put the water tubs and food bowls on top of it. Underneath, I laid down a layer of pea gravel. It's been working pretty good so far at keeping the run from getting muddy. I also lay down a mix of wood chips, straw, and hay in the run and stir it up every few days. My chickens are in with the ducks and they do a good job of stirring it up so it can dry out. If some areas are just too damp, I toss that and add some dry materials. I don't have a kiddie pool in my run. My ducks just swim in the water containers (cat litter box and round rubber bowls). They seem happy and the run is pretty dry. We haven't had rain in a while, which helps, but my run is completely covered with tarps to keep out some of the wet. I don't know if this is helpful to you at all, but just thought I'd share what seems to be working pretty well over here.