The potential Hooverville neighbors would throw a fit. Anything sanctioned would run into all sorts of political (and legal, and liability?) issues. But simply don't enforce nuisance laws for a given area, and let a nonprofit locate a clusters of port-a-potties and mobile showers there as more homeless show up...
In any West Coast city there's also the issue of where to locate any major Hooverville. I'm thinking 1,000-person places. Any multi-acre empty site probably has a development coming. So maybe the key is to do 5-10 smaller sites. Even then, who wants to live, work, or play next to 200 people who won't follow shelter rules?
Some non-profits are already doing "tiny house villages" that have staffing and rules and aren't very big (making them politically palatable). They tend to be on small, temporary sites like church parking lots or
pending development sites. We need more of these, but we also need something for the people they won't take.
PS, the Hooverville south of the stadiums was
nine acres and housed up to 1,200 people from 1931 to 1941. These were common nationwide. Most residents probably wanted to work and simply couldn't earn enough, an important difference vs. letting drug addicts run wild (counter to my idea)...