As the folks over at Tiny House Blog describe:
The entire trailer weighs 3,800 pounds and it took them three years to build. The rafters were made with laminated pine boards and the floor with locally milled sugar pine. It is insulated, contains a small kitchen and electricity. They have a camping toilet in the closet and a solar shower that they keep in their tow vehicle, but the couple usually use campgrounds, friendly locals and universities for their bathing.
Check out this cool wagon over at Tiny House Blog.
(Images: Tiny House Blog)