Sheep wagons in the US historically provided the same kind of shelter facilities as shepherds' huts have done in the UK. These attractive structures - similar to European gypsy caravans - are of course also ideal for shedworking as the fine folk at Idaho Sheep Camp point out. Run by Kim Vader, who comes from a family of sheep herders (many of them Basque - the Basques were some of the earliest sheep ranchers to use these wagons), their wagons are built in Boise Idaho. The floor and side walls are built with tongue and grove, doors in Birch and pine, as well as wood stoves. Examples are pictured above and below.Also of interest is Ogden's Sheep Camp which offers a modern version and if you're looking for a good book on the subject, Sheepwagon: Home on the Range by Nancy Weidel will be right up your street. And for more history, go to Wilson Sheep Camps.
Thanks to James Westwater for pointing me in the wagon direction