Sections 29004 and 29005 shall not apply to trailers or dollies used to support booms attached to truck cranes if the following conditions are met:
(a) The trailer or dolly is connected to the boom by a pin, coupling device, or fifth wheel assembly.
(b) The trailer is secured to the boom with a chain, cable, or equivalent device of sufficient strength to control the trailer or dolly in case of failure of the connection consisting of a pin, coupling device, or fifth wheel assembly.