Hello Abe,
Hopefully this will answer some of your questions.
See:
45' Motorhomes
Over-Length Motorhome: An over-length motorhome is a single-unit motorhome that is longer than 40 feet but not more than 45 feet. (Note: A vehicle combination, e.g. a motorhome towing a vehicle or trailer, may be up to 65 feet length. If the single-unit motorhome is 40 feet or less in length, the combination is not subject to the route restrictions for the over-length motorhome.)
Motorhome: A motorhome is a noncommercial passenger vehicle defined in the California Vehicle Code (CVC) Section 465 as a "house car" and commonly referred to as a recreation vehicle. CVC 362 defines "house car" as "a motor vehicle originally designed, or permanently altered, and equipped for human habitation, or to which a camper has been permanently attached." A motorhome should not to be confused with a bus (CVC 233) or a tour bus (CVC 612), also called "motorcoach," which is used for commercial passenger transportation and requires a commercial driver license to operate. See also Public Utilities Code 5360-5379.5 and 226.
BACKGROUND
The basic California length law for vehicles is 40 feet unless specifically exempted. On October 9, 2001, Governor Davis signed Assembly Bill (AB) 67 which changed the California Vehicle Code (CVC) to allow motorhomes over 40 feet in length, up to 45 feet, on certain routes. Over-length motorhomes are allowed on interstates and on those State routes that can accommodate them.