Cal. Veh. Code § 242

A “camp trailer” is a vehicle designed to be used on a highway, capable of human habitation for camping or recreational purposes, that does not exceed 16 feet in overall length from the foremost point of the trailer hitch to the rear extremity of the trailer body and does not exceed 96 inches in width and includes any tent trailer. Where a trailer telescopes for travel, the size shall apply to the trailer as fully extended. Notwithstanding any other provision of law, a camp trailer shall not be deemed to be a trailer coach.