Cal. Health and Safety Code § 18604

(a) No manufactured home, mobilehome, or recreational vehicle within a park shall be rented or leased unless it bears a label, an insignia, or an insignia of approval required by Section 18026 or 18027.3, or a federal label issued pursuant to the National Manufactured Housing Construction and Safety Standards Act of 1974 (42 U.S.C. Sec. 5401 et seq.). (b) A recreational vehicle that does not bear a label, an insignia, or an insignia of approval, as required by subdivision (f) or (g) of Section 18027.3, may not occupy any lot in a special occupancy park unless the vehicle owner provides reasonable proof of compliance with ANSI Standard No. A119.2 or A119.5. A department label or insignia shall constitute one form of reasonable proof of compliance with ANSI standards. This subdivision does not apply to a recreational vehicle occupying a lot in a special occupancy park on December 31, 1998, unless the vehicle is moved to a different special occupancy park on or after January 1, 1999.