Oh - KDOT specified Type A lab trailer. We lease or purchase these through Satellite Shelters in Kansas City. I think they are pretty pricey as they are "certified". They come with drawing tables, desks, 100 gallon water storage w/ electric pump hooked up to sink and a stove. Also, have AC & heat. Should be able to do a search for Satellite Shelters.
I do have one shell which is for sale for $250. It isn't in very good shape (hence the cheap price). It does not have AC, the stove, or the sink, but does have a propane heater. I believe measurements are about 8 x 12 or so. It would be pretty easy to convert it to his needs - gives him an open shell to start with.