I built the trailer and floor first, matching the mounting holes in the underside of the floor to the trailer, then took the floor up the stairs to the loft of my friends barn, where I am building the cabin. The proverbial 'ship in a bottle'.
When completed we will lower the cabin down thru the shipping hatch in the floor and land it on the trailer.
This allowed me to use the floor as a work table on saw horses, then drop it down onto a cradle once the walls were up. Simple step up thru the front opening while working on interior details before the front cabinets and roof went on.
So not only is it a practical way to build, it might suit certain work shop scenarios better. Some people, on the other hand, might find it easier to move the cabin in, out and around while it is mounted on the trailer.
Pick your choice.
