Its very fun. I kind of pseudo did it. I went to the west coast and slept in a national park a few times illegally, beautiful. I went to portland oregon and slept under a bridge one night with a homeless crowd (all by choice). It was fun except they were all very stupid. They were smart, but stupid, you know? Like they hated money and everything but didn't know why so they abused their bodies, were always trying to get "fucked up", etc. I hated portland but I loved what I learned from it.
I then slept on the side of a high way the next night, woke up to a girl collecting cans (god she was gorgeous though, very weird).
Its very fun. Don't commit to it - have goals, have aspirations, have some kind of meaning to your life other than drifting and getting free shit off of other people, but the knowledge and experience you gain is incredible. Not to mention you come to terms with the value of objects and stuff to a much greater extent.
(also always carry a knife or a weapon - while I was in portland many of the people told me they had gotten their asses either beaten or beaten someone else for a small amount of money or liquor.)
PS: It is a very interesting ability to say "Yes I was chose to be homeless for a while" the stories you gain will last you a life time.