I felt compelled to respond to the comment, but the article is interesting too.
http://realestate.aol.com/blog/2011/06/01/video-family-lives-in-320-square-foot-shotgun-shack/?ncid=webmail#aolc=A1CQ8g
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.