I would be wary of using cardboard boxes. In the past, I've had to sign a liability waiver when checking something in a cardboard box.

That said, you might also want to consider a couple of basic ideas about strategic packing of things versus clothing. First, make sure your luggage (or box) is completely, totally full. Any empty space needs to be filled with something, even if that something is as mundane as an empty plastic water bottle or dirty clothing.

Second, bear in mind that for most of the journey, any luggage will be in what we might consider upside-down position, with the wheels in the air (this is so it will slide around less). And that you should be packing with the assumption that someone will, at some point, throw or drop your bag with far less care than you would use to move it.