The DOT requires 8' or 8' 6"" for a sleeper. We used to make these back in the early 70's. Also a 125 gallon gas tank underneath them. You could crawl up and sleep in them but they really weren't very comfortable. They were insulated but it was still either too cold or too warm in them. They usually wound up being a storage area for about anything. They squeeked and leaked too even with the big donut that someone came up with.
A crew cab with four or five guys riding got pretty ripe after a race. The trailers then got longer for small living quarters. Mostly for a shower and potty. Them that became a problem to keep clean and emptied.
The evolution continued to the semi tractor and 53 foot trailer with a lounge.
So the beat goes on and now you have multiple car and equipment tractor/ trailers with a special hospitality trailer. The crews rides or flys and stays in a motel when on the road.