I don't understand why people think shipping containers are a good idea for housing. They were never designed for this and will always be compromised when you come to put windows, doors, insulation and services in them.
This wasn't a bad series: https://www.youtube.com/watch?v=QA5fh29rhLs
Put me in the 'shipping containers make shitty houses' camp.
Could have just built a wood frame house. Quicker, faster and more roomy.
Cut out a whole side wall? That's a very different story.