If you are not an idiot, people leave you alone for the most part. The police are probably (understandably) tired of dealing with the homeless there, so they arent always the nicest. if you arent being disrespectful, or fucking around with their drug market, the gangs will leave you alone. I got pretty close to having a problem, trying to drop a few ounces of grass from portland there, but when they realized I didnt have so much, and I was just a dumb kid, they let me alone.
I really would reccomend sleeping on the beach, and if you do, head down right near the pier. they take a tractor witha giant rake over the beach some nights, and I have seen a few kids lose all of their shit, because the tractor drivers are also quite tired of the bums, and wont slow down while you are waking up and trying to get the fuck out of the way without losing anything.
There is a parking lot near the post office and library, about 1 km from the beach, everyone on homebum hill knows where its at, probably get an early morning wake up, and keep all of your shit tight and close to you, as you will be sleeping around tons of fucked up junkies and the likes. Its really easy to get by though, try not to get stuck too long. the only place I will spange, as it is too easy to make 100$ a day there. unfortunately, its soo easy you often spend it all on you drug of choice (I had my own weed from portland, so for me and crew it was just top shelf liquor, and the occasional lsd, though pretty much everything is available), and wake up wishing you had money for coffee.
Have fun, and keep yer dick wrapped, theres lots of pretty young beach girls there that are total hobosexuals, and dont think that you are the first crusty nasty bum she has fucked.