All the "swivelwheel" type trailers, be they the Idaho Tote, SwivelWheel, or Smart Trailer, work basically the same way: the trailer is solidly mounted, other than up and down pivot motion, and the wheels move to allow for direction changes. The only thing that differs is how the trailers mount to the 5th wheel, and how the wheels turn. They are not permanent additions, and can easily be removed. To me the phrase "easily removed" makes them a trailer and not an extension.
However, all the debate in the world won't determine what the LEO's say about them, and that is what counts. I traveled a lot with one and was never stopped, ever. You say "tomayto" and I say "tomahto", but if he says "broccoli" that's what counts. :)