Class IV: six other citizens of the Township to be appointed by the Mayor. The members of Class IV shall hold no other municipal office, position or employment except that one member may be a member of the Zoning Board of Adjustment and one may be a member of either the Board of Education of either the Freehold Regional High Schools or the Manalapan-Englishtown Regional Schools. A member of the Environmental Commission who is also a member of the Planning Board as required by N.J.S.A. 40:56A-1 shall be a Class IV Planning Board member unless there be among the Class IV or alternate members of the Planning Board both a member of the Zoning Board of Adjustment and a member of the Board of Education, in which case the member of the Environmental Commission shall be deemed to be the Class II member of the Planning Board. For the purpose of this section, membership on a municipal board or commission whose function is advisory in nature, and the establishment of which is discretionary and not required by statute, shall not be considered the holding of municipal office.