If you want a shop and the "secured storage" that you feel you'll be getting from the containers, why not build a regular post frame shop with a lean-to on one side to put a shipping container under. That way in a few years when you realize that shipping containers are not that great for long term storage in most climates, you don't have to tear down and start over. You can just get rid of that one container and still have the lean-to for something else.