I'm going to build a chicken feeder, meant to store lots of food at once (40-80lb). The design is like a silo-like structure, with a box under it. I'm attaching a door near the bottom of the "silo" and it pours into the box underneath. The box is level to the "silo" but I can't think of a way to prevent it from overflowing when I open the door. Any ideas? Thanks!