If the director approves and fixes a single assessment, the advisory board shall recommend and the director may approve the proportions of such assessment which may be expended to defray the costs of formulation, issuance, administration, and enforcement of the marketing order and that which may be expended for such advertising or sales promotion program. The proportion of such assessment which may be allocated in such manner to defray the cost of such administrative activities for such marketing order shall not, however, exceed the maximum amount which is authorized in Section 58924.