Look at a refer trailer and that way you get the added insulation. Look into getting it wrapped. Many of the service trucks around here have the wrap and it is amazing how well it hides doors, windows an handles. Can't speak for there but in CA it is just a matter of a CHP inspection and DMV paperwork and fees to get it reclassified. Look into getting the Semi reclassified as a MH (may have to add a sink, bed, etc.) and that might also eliminate the need for a special CDL.
My FIL built a house on a 53' flatbed trailer so that he could easily move it someday. Someday never came but the trailer made a strong foundation.