Nobody should be forced to sleep rough, in the cold and dirt, where they are vulnerable to rapes, theft and beatings, such a life turns the kindest soul into an animal. 20 sq. feet of lockable closet with a mattress and shelves to store one's minimal belongings could mean maintaining their humanity and preventing turning them into dangerous criminals.
This would be so cheap to offer that it could be a basic human right, I would certainly pay taxes for it before other stupidities promoted as measures against crime. It's definitely not an incentive to be poor, those who can afford can rent a larger space, it would be a minimal guaranteed, free baseline: no matter how bad you fail in life, you will still get to be treated like a human being.