(a) The Certificates of Number for dealer, manufacturer, livery vessels, commercial vessels of less than five net tons and vessels carrying passengers for hire shall be clearly marked to show the vessel use.

(b) All applications for numbering of such vessels shall be submitted directly to the Department of Motor Vehicles, Sacramento, who may upon approval after the payment of the required fees issue a vessel number with distinctive suffix letters.

(c) Dealer or manufacturer numbers shall only be temporarily attached to the vessel during demonstration or test period and are valid for that period of demonstration or test only.