Thanks, good suggestion about the foam plug. And yes, it is made of wood and I wasn't sure what to call it since it isn't really a "door" and it also isn't a wall/drywall. I've gotten lots of conflicting advice here so I'm trying to consider everything, but trying to drill through my drywall, insulation, and vinyl siding (like many have suggested) just seems like a much, much, much more likely to cause problems approach.