Best way to handle a late night knock on your door

I've been RVing since the 60s. Only had one guy knock on my door. He was a park ranger telling me that there were empty sites now available. ( I was in an overflow area) Since I was in my bathrobe he said moving in the morning would be OK. That said, if you have any weapon you best be sure who you are pointing or shooting at. Even LEOs are going to jail these days for bad decisions and they are trained to use firearms.