(1) Policies of insurance in regard to bodily injury and property damage liability and cargo insurance, proof of which are submitted to this commission by way of certificates of insurance must be written by insurance companies who are authorized to conduct business within the state of Montana, as required by the state commissioner of insurance.

(2) Insurance policies themselves need not be filed.

(3) Certificates of insurance must be filed with the commission. All certificates of insurance submitted by insurance companies on behalf of the respective carriers must be executed by an authorized company representative.