How about electrified walls. That might deter these degenerates from such a disgusting habit.
The problem is the number of homeless people, who number enough to start their own city and get a zip code.
They “Have rights” you can’t imagine and this is about the politest way of dealing with them.
Thing is they aren’t stupid and they’ll quickly learn to stand perpendicular the any phobic object and nothing will change...
What happens when you actually urinate on a electric fence...
https://www.youtube.com/watch?v=iwKlFkX65Zs