Tent Cities: they're common, they can work and they are justified

Occupy camps were intended to protest inequality, but they very quickly turned into tent cities for the homeless.  In that respect there was nothing unique about the Occupy camps, because tent cities are already common in North America.  Here's a link to a series of news stories documenting the situation.* 

I don't think it's correct to say that tent dwellers are homeless. I've seen what happens to street people who move into tents. They feel pride, and a sense of community. Having a place that's yours (even if it's just a tent) means having a home, and that's a huge step up from sleeping in shelters or out in the rain.

Occupy Vancouver is an unusually well organized tent city.  It has a tent library, tent places of worship, a tea  tent, a medical tent staffed 24/7 by volunteers and a tent community kitchen. It has a municipal government (the general assembly) which the community recognizes as having authority to pass bylaws, and it has a volunteer security force charged with keeping the peace. The OV tent city is a tent city, and I hope that more North American tent cities come to have similar institutions.  

Question: do tent cities have a right to exist?

I think tent city dwellers have some rights to the land they're encamped on, and some right to govern themselves rather than fall under the jurisdiction of a hostile neighboring municipality.  I'll need to think more about that, but for the moment I'll just drop this strong reading of Locke's 2nd Treatise, section 36:

Supposing a man, or family in the state they were at first peopling of the world...let him plant in some in-land, vacant places of America, we shall find that the possessions he could make himself...would not be very large, nor, even to this day, prejudice the rest of mankind, or give them reason to complain, or think themselves injured by this man's encroachment. 

But of course we are not in the state of nature, because the invention of money, and the tacit agreement of men to put value on it, introduced (by consent) larger possessions, and the right to them. Because we all agree that our financial system is just, municipalities and absentee landlords have the right to use force to ensure that their vacant, neglected property remains vacant and neglected.

* I comment on metafilter as justsomebodythatyouusedtoknow, in case you were wondering why my post here looks a lot like some comments there