Without piling on and seeming cold, *I* can't afford to live in Berkeley either. If you're employed (as some say they are), can't afford housing and are squatting (sorry, that's what it is) on property where if I parked my rig I'd instantly be required to move or be arrested and towed, then you are making a decision. The reality is, you have to pick up and move where your job can support a dwelling of some type, whatever that may be - this is the same decision every single one of us has to make, it's not unique to the RV dwelling homeless. To attempt to turn this into a situation where the government is supposed to make allowances and somehow accommodate the situation is a straw man argument. That said, many of the squatters in the "houseboats" in Marin county did pretty well. For years they were threatened and eventually their 'encampment' was legitimized (I have been out of touch with that situation for many years so my info may be very out of date).
"Choice" is a very broad brush and I don't mean to ignore the plight of those who are truly in need of a safety net, but I don't think that applies to many of those in this case. Again, can't afford an RV park in the Bay Area? Neither can I.