You are going to laugh at my exterior, but I believe it'll work great. I'm covering it in a very thin wood, then gluing canvas to it, painting it to get the color I want, the waterproofing it like crazy. The bunks are sloped. 5" from from the inside to the outside. And what's going to keep the weather out is of all things, rubber baseboards. They are flexible and will go up with no problem, and should keep everything out, or in as the case may be. Here's what I've done so far (I've fixed a few of the things on there since I took these pic's).