Early work vans were designed to house manual laborers when on the job. Great for highway and railroad crews. These caravans were noted for poor ventilation and their spartan interior. Three to six workmen were often housed in these wagons.
All the necessities for living with none of the comforts of home. Cheaper than regular housing and mobile too. One can see how this evolved into the later caravan. These were expensive and not as well thought-out as later ‘vans.
Preindustrial Craftsmanship 
In New Zealand, where I live, these wagons were called ” Stinkies”. They were pulled by the steam powered traction engines along with a mill. The mills were used to thresh grain. The mills moved from farm to farm with their attendant crew of workers in the early 20th century. The stinkies slept around six men. I can imagine the fug inside the stinkie after a long day in the hot summer sun for the men who had to sleep in it.
The funk would be thick in such a space.