Best way to handle a late night knock on your door

We have never been approached in a rest area, truck stop or Walmart. I don't often stop for very long in a truck stop anymore as there are not enough spaces for all the trucks and the truck drivers do not appreciate MH's in their spots. As a former trucker the only times I was ever approached anytime was in truck stops by ladies of the night. You could see through the windows what was going on and ignore them. Never anyone who wanted to hurt, rob or steal in 27 years over the road.