Ah the sound of a fleet of trucks putting their boxes up on a Monday morning after a rainy weekend. If you leave the box up, don't allow the first segment joint to be exposed. We've had trouble with water getting in and freezing. It's not going to rust the box out unless you plan on sitting for years. Our boxes are heated and the sills under the floor lay full of water from condensation all the time, and I have never seen one rust through. Even in dry weather, water comes out by the hinge pins every time you dump