I think you need to look into a toy hauler like others have said.
Do you need that much office space? What kind of work do you do? How many workers?
Wife an I are both photographer / journalist and full time. When we first hit the road thought we needed huge amounts of office space and over time our office needs have shrunk.
We have two 6' desks that we switch back and forth between them depending on what were doing. The one desk is set up with a desk top for photo editing / file server. The other desk has a 2 drawer file cabinet and an all in one scanner printer. We do most of our work on lap tops and use the desk top only when needed.
Don't forget about the amount of power that will be needed to run office equipment. Office equipment puts out heat so you will need more cooling. Make sure you look at you power needs with the trailer before you buy anything. A 30 amp (120 volt) power system dose not go far after the converter is on and the AC.
