Easy... Outdoors RV. They began in the former Fleetwood plant that built the Wilderness 4 seasons trailers in Oregon. Started by Ron and Sherry Nash, and a sister company to Northwood (Arctic Fox, Nash).
He'll have to go out West (or have it shipped) to get one, but based on your description, he'll have a hard time finding a better built trailer for his intended use. (A number of folks on the East Coast have done just that).
Outdoors RV constructionEdit: I posted the older version of the video, I thought it had better technical information. Product line names and classifications have changed a bit since.
Example of a 28' bunkhouse layout in their Timber Ridge class:
Outdoors RV Timber Ridge 27BHS