Hard to think of this as a first. At the time, wagons like this were in very common use, by travelling artisans.Brian Peacock wrote:The Wanderer, the World's first custom-made leisure touring caravan, was built in 1885 by Bristol Wagon Works Company for Dr William Gordon Stables.
This might be the first recorded purely for leisure, but they were a common sight for various trades.
This is one used by travelling brush makers, which was a respected trade and way of life throughout the country by 1850. They would both live in it or rent rooms, depending on what was available.