I don't really have anything to add to this, other then I thought I would share a couple of pictures of a container barn that they started/built about the same time you did yours. I remember thinking, I've never heard of anyone doing this when I read yours post. And low and behold there was one being built before my very eyes. I wanted to get some pictures of the construction, but between forgetting my camera and the time I was going to and from work it didn't work out. I did manage to get a couple of shots a couple of weeks ago.
It looks like it is 4 containers long and 2 containers high or a total of 16 containers.
Sorry about the quality of the pics, but they were taken through the car window at about 60 MPH. Here is the first one of the one side.