Big thank you to Anna for all your help in figuring out this system. Anna suggested cotton mats as being a material cats won’t pee on. I also sprayed them with vinegar which is meant to discourage them from peeing.
After almost three years I finally have a solution to make my house not smell of cat pee and to have a welcoming back door. Thanks also to Monique for the shoe rack and for Leanne to introducing me to broom grabbers. This all means a huge deal to me.
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So far the cats are still peeing on the mat closest to the door but at least it’s very low stress to clean! More iterative attempts at solving this is required.