The said commission shall serve at the pleasure of the governing body of the political subdivision. Should said governing body not create the said commission, or should it determine following its creation to revoke the authority of and terminate the said commission, then the powers and authority hereby reposed shall vest in and be exercised by such governing body, the board of supervisors of said county or the governing authority of said city. Such governing body shall by appropriate order fix or approve the rules and regulations of the commission which shall assure that all the costs of administering the bridge properties shall be exclusively borne from bridge revenues and not from any funds derived from taxation; and said governing authority shall by appropriate order fix or approve the compensation, if any, of the commissioners and the extra fees and reasonable allowances to be paid to the clerk of said governing authority to reasonably compensate such clerk for the extra services and work hereby required. The combined total of all of such costs of administering and handling said funds, as above in this section particularized, shall not exceed seven and one-half percent (71/2%) of the aggregate sum of the funds received from such bridge revenues and regulated by the provisions hereof; if the commission not be created or be discontinued, such percentage shall be not more than five percent (5%), and no member of the board of supervisors or governing body of such municipality shall be authorized by Sections 65-25-49 through 65-25-61 to receive any additional compensation.