As long as it is a legal stop sign (size, shape, color) mounted at the regulation height, it could be citable. We just tend to stay away from private property. Even though we don't take non-injury or non-hit skip accident reports, I have still been ordered to. About 5 years ago I arrested a 17 year old for reckless op. on private property. He had been playing Grand Theft Auto all day and decided he wanted some food from Taco Bell. The problem is, he had absolutely no idea how to drive, and certainly not a stick shift. He stole his mom's manual Astro Van, was banging it through the gears, then rolled it over in the parking lot. On top of all that, he was drunk also.