Constitutional rights be dammed!
Remember when we had a thing called vagrancy laws?
If you're a vagrant AND commit a crime, you go to jail or a mental institution.
Don't do the crime, if you can't do the time.
Simple as that.
Homeless shelters for those truly down on their luck, but drug/alcohol free.
If you stay longer than a few weeks or couple months, you need to earn your keep doing community service.
Do excessive drugs or alcohol? (getting $$$ somewhere for habit, usually crime) Send to rehab shelters that you can't leave until clean.
How can that be unconstitutional?
Letting homeless have free run of the streets and cities make as much sense as vegan steak sauce (yes there is such a thing).