North Carolina by Rich’s Portable Cabins
Because he builds the frames from the ground up, these homes are the maximum legal width and so low that you can stand upright in most of the lofts.
A great article about the Charles Finn Microhomes. Wonderful designs as small as 8 X 12 (96 sq ft)
Charles’ website: A Room of One’s Own
An abandoned Victorian tree house somewhere is South Florida