Hi--I may be of little, if any, practical help but I want you to know that you're not alone. I have only one cat but he feels free to pee and poop anywhere and everywhere in and on the mountains of filth and clutter with which I'm surrounded. Most of the time I feel ashamed, paralyzed, and unworthy of even the most basic human respect. Knowing that I'm not alone, though, helps a lot. I would never judge someone else as being unworthy of respect--quite the opposite. I commend you for having the wherewithal to clean it up. The best of luck to you.

I would use a shovel.
Honest.
And wear coveralls, gloves, boots and a very good face mask.