Dude, there are so many threads on this. Either look through the content on my profile, or search "public land" in the search bar. I would quote some threads but I am kinda up to some other stuff ATM.
I did an entire write up on the laws living on public land, I just cant find it at the moment.
Highlights:
-you can stay up to 14 days on any piece of public land (BLM, Forest Service, Fish and Game...) unless otherwise specified (Not always posted)
-After 14 days you usually should move at least a mile to another spot to satisfy said local Ranger.
-if you are far enough out, sometimes this rule is flexible.
-Always do research on an area, and read local regulations
-Clean the FUCK up after yourself. Im sick of seeing assholes leaves behind piles of trash after their "off-the-grid" spot is done with
-State land rules vary
-The forest service has become much more avid about "confiscating" personal property at camps that have been there for a while. Watch out for this. If a wildfire comes through, they will block off the area and throw away your shit. Seen in many times in Oregon.