There's several corners of forest land in San Diego county, that touch private and you must literally step over that marker with one boot, not two.
Here is a story, great spot, It's riparian and loaded with turkeys and poison oak, extremely brushy, and completely surrounded by private land. I saw a group of hunters, the Sherrif, adjacent land owner, Vista Irrigation security, Game Warden and a dead Jake. I parked a hundred yards down the road and walked over and talked to the adjacent land owner and Vista guy. What happened I ask the land owner and Vista guy? Land owner said those guys trespassed on my private land!! I said, what do you mean, show me on my map? And he did he pointed to a letter on the map and said those guys were sitting right there on my property. I asked how do you know? This was befores GPS units had maps. I said there are no fences and it's so brushy how can you pin point a precise spot? He said he just knew where they were precisely, because he had spent a lot of time in there. I asked, do the hunters agree they were where you said they are? He said, no they said they were not on my land. The spot according to land owner was 50 yards into his property. I said was the Warden with you when you found them? He said no. There was no fence or boundary marker.
I have no idea who was telling the truth and either the hunters or land owners were wrong. Only way to prove 100% would have been to make hunters sit where they were, or mark with paint where they were, bring out the Warden and a licensed surveyor to plot their exact location.
My gut said the land owner was wrong after talking with him. Also, some property owners, could have been the same guys private land owner, different guys posted public land as private about 300 yards away on a cross road. I saw them and they told me they posted the signs and besides there are no turkeys here, we know we live here. Later on the Forest Circus removed the posted signs. Yea!!!