Amphibious Trailer

A 'fifth-wheel' is a travel trailer supported by a hitch in the center of the bed of a pickup truck instead of a hitch at the back of a vehicle. The special hitch used for fifth-wheels is a smaller version of the one used on 18-wheeler trucks and can be connected by simply driving the tow vehicle under the trailer. Fifth wheel trailers are popular with full-time recreational vehicle enthusiasts, who often live in them for several months in one place, using their pickup truck tow vehicle for local errands. A fifth wheel trailer tows more securely than a traditional travel trailer because the hitch weight sits directly over the pickup truck's rear tires. Since part of a fifth wheel sits over the bed of the pickup, it also reduces the overall length of the vehicle/trailer package while allowing the same room as a comparable length travel trailer. Additionally, the hitch's location in the pickup's bed reduces the risk of jackknifing and allows for more manueverability when backing. Because of the greater room available on the roads in North America, these vehicles are more popular in the United States and Canada than in Europe or other parts of the world.
Double-decker trailers
A double-decker trailer is a two-level travel trailer. When traveling the trailer is only as high as a regular trailer, but when set up it increases in height to two full levels. Built by Jexcar and others, they are often used in motion picture production as portable dressing rooms.