Mobile Saunas, by Kārlis O. Kalniņš, is a unique book with hundreds of photos and hundreds of (nomadic) saunas around the world. It's expensive, because it's a Hulu color print-on-demand book, but then again, $60 might not be too much to pay for an idea that could say, lead you to to turning an old VW bus into a portable sauna.
Here's what they say: "This is a collection of sauna trucks, sauna buses, sauna wagons, sauna cars, sauna bikes, sauna trailers, sauna boats, sauna floats, trail sweats, bastuflotten, bastubats, banya trucks, banya tents, and other mobile sweats. They are gathered from across North America, Russia, Europe and particularly Finland, where the annual Teuva mobile sauna festival attracts over 50 examples every year. After building several mobile saunas, Kārlis began a multi-year study of the mobile sauna phenomenon in form and culture. Collected here is the result of that study, including photographs, viewpoints of builders, commentary and notes on design.
Students of culture and architecture, sauna lovers and mobile sauna builders will appreciate the variety of forms, designs, styles and ideas revealed in this volume."