My 2 squirrels may winter over in a horse stall with rubber stall mats. Will the squirrels choose a certain spot to pee and poop or will it be random? In their current cage they don't pee or poop in their nest box. I use puppy pee pads in the bottom. That is not practical in the large stall I could place pee pads in a corner if they will use it or I can cover the 12x12 bottom with cat litter, pine shavings or PDZ, a clay product for horse stalls and chicken coops.