I felt compelled to respond to the comment, but the article is interesting too.
You "home eded" your kids? I hope their spelling, grammar, punctuation and phrasing are better than yours.
Also, the lot rent they're paying exceeds what I pay for my mortgage on a house 5X that size. They don't actually "own" a home. They own a trailer on someone else's land.
Then, the new laws on child products may put their little business under. I disagree with these laws, but compliance is something all businesses have to deal with. They may be in a world of hurt shortly.
I also wouldn't allow the kid to stay up there for "2-3 days at a time." As someone else said, he's living like a squirrel. Also, fire code in almost every jurisdiction requires two escape routes from all sleeping areas. He seems to have one ladder entrance only, and that directly over an ignition source.
As a cabin for a summer camp, it's smaller than either of my tents. As a house, it's smaller than my garage and of questionable safety.