Except this create is not really a shipping container, but a crate used in a circus. Which is supposed to contain dangerous creatures. And from what I recall of my youth when circuses actually existed, would be kept outdoors as a matter of fact. So the rotting/waterproofing part of it would still be at the forefront of their concerns.
@Hardcore: we are using Occam's razor. The assumption that oak was used is precisely an application of Occam - one side arguing that it is the smallest assumption since it is the logical wood to use, the other side arguing it is an unnecessary assumption because softer woods could have been used instead.
Now, if you refer to magic being in play, I agree. I argued as much for the wizard spells, extra magical objects and the non-evidenced Mantle bonus. But even with those discarded as per Occam, there is still other assumptions whose respective weights are in contention.
Grey Wolf