Families types matter when you are trying to get information out of them meaning you want to pick that data out of a schedule. But the Schedule can only pull whats in the families parameters and what the schedule is capable of finding in that family. I would have to ask you what data are you needing from the shipping containers and let that answer drive my answer from there. Because I can make a family as a generic floor based, floor based, generic (floating) any type I want for the most part because a shipping container is typically a rectangular box, and I am not so concerned with how it looks as apposed to overall dimensions because as an architect when it comes to families I am thinking about planning for space considerations to coordinate with. If you are wanting to render it, most likely its going to need to be a little more accurate in appearance so it could become challenging but could be done it just might end up being to large of a family, typically you don't want to exceed 2,000 mb if you are copying it around. If its a one off then a little larger in file size will be okay. I looked on a external site and its a collection of models of all different software, and it seems no one has modeled one with revit or at least put one up there using revit. https://grabcad.com/library?page=1&time=all_time&sort=recent&query=shipping%20container theres the link, Revit can recognize some of those file types and then it could be placed inside a revit family and place it into a project.
