That's a difficult situation. I shoot lots of time lapse. I can't imagine expecting to just own a place like Delicate Arch or any other place in a National Park for a shoot. Would I hope no one else shows up? Yes. But if other people show up I might chat with those people to try to help minimize impact to what I was trying to accomplish while also helping them get what they want. If it ends up ruining my time lapse, then I would simply have to try again. That's life. Be kind to one another.