This really isn't that hard, is it? If you're concerned about someone barging into your room, put the slider/deadbolt on when you're in the room. If someone comes knocking and wants access to the room, I'm sure it's reasonable for you to ask them to present ID. If you don't believe them for some reason, I'm sure it is also reasonable for you to tell them that you want to call the front desk and confirm their identity/purpose before letting them into the room. I mean, I've always assumed that a resort employee could and would access my room for maintenance or other legitimate reasons and used the slider/deadbolt specifically when i wanted to restrict their entry.