Can the cops kick my off of someone else property ,when I am support to be there to watch the place?

This guy let's me park my rv on his car dealership place. So I can keep a eye on it at night.like a night job u can say.can the cops kick me off of there and say I can't be there at night or any time?

Car dealership :/
If its outside of the area, than yes they can tell you to go away.
if its inside the dealership, no they can't