You can go on line to see AZ state trust land maps. They offer a few different on line passes for camping or atv use. I paid for atv use and saved a copy of the transaction on my phone and taped the permit number on my ATV. Some of the areas will be gated but just close the gate aging when you pass through. Often times it isn't a real gate, just strings of barb wire on posts which need to be secured after you pass through.
You may be riding a trail and come to a section which is state trust. If you look at the maps it will sometimes look like a checker board.