Spent 15 years living it man, I'm not joking when I tell you that the solution to your problem is to move.
Confronting a homeless junky is not a good idea, you're confront someone who literally has nothing to lose and all day to fuck with you.
LEO's in areas with a high volume of homeless are completely demoralized and checked out, they aren't going to give you the time.
Cameras and security lights are a joke. There's an assumption there that the violent schizophrenic fentanyl addicted sex offender has some level of shame and doesn't want to be filmed taking a shit on your door step. Pro-tip: He doesn't
By the off chance some scheme in this thread works, it won't be too long before you're dealing with the same issue but a different junky. If a city tolerates homelessness even a little, you'll quickly end up with a lot. . . It spreads like cancer.
You should consider moving. I did and it was the best decision I've ever made.