I had some stupid landlord problems last spring and it took a while to find a new place I could afford, so I was staying with friends, sleeping in my car, and so on. From that experience I'll say a good place to be homeless is someplace you know really well, because it's easier to find a safe & hidden place to park the car for a few days, and I knew a lot of places to use the bathroom, get cleaned up, and to relax during the day when I needed to.
I was surprised at how many other people were doing the same thing.