The RVIA has provided a table showing regulations by state for park model RVs
What is a park model?
Below is a description from the RVIA:
On July 1, 2012, RVIA created a new membership category for manufacturers of park model RVs (PMRVs). A park model RV (also known as a recreational park trailer) is a trailer-type RV that is designed to provide temporary accommodation for recreation, camping or seasonal use. PMRVs are built on a single chassis, mounted on wheels and have a gross trailer area not exceeding 400 square feet in the set -up mode. They are certified by their manufacturers as complying with the ANSI A119.5 standard for recreational park trailers.
PMRVs are most often used in recreational vehicle campgrounds. They may be owned by the campground and rented to guests, or they may be brought in and used exclusively by their owners on a site rented or leased from the campground. They can also be placed by their owners on private property. These RVs are used for recreational purposes only. They are not meant to be permanently affixed to the property, they do not improve property values in any way, and they are neither designed nor intended by their manufacturers to be used as permanent residences.
Two different types of park model RVs are offered. One type is less than 8′ 6″ in width and is designed for frequent travel on the highways while the other and more popular type is wider than 8′ 6″ (usually 12′ in width), and must be transported with special movement permit. The 8′ 6″ unit typically is expandable when it reaches its destination utilizing slide-outs or tip-outs. The wider units, being less mobile, are usually sited in a resort or RV park location for an extended term, typically several years. Park model RVs are titled as vehicles by the various states. This is because PMRVs are built on permanent chassis such that they can be and are moved either within a campground or between campgrounds.