Every highway commissioner with 5 or more employees in a county under township organization shall set and adopt rules concerning all benefits available to employees of that office. The rules shall include, without limitation, the following benefits to the extent they are applicable: insurance coverage, compensation, overtime pay, compensatory time off, holidays, vacations, sick leave, and maternity leave. The rules shall be adopted and filed with the township clerk (i) within 6 months after the effective date of this amendatory Act of 1991 (in the case of highway commissioners holding office on that effective date) or (ii) within 4 months after the highway commissioner takes office (in the case of highway commissioners elected after the effective date of this amendatory Act of 1991). The highway commissioner of a consolidated township road district shall file the rules with the clerk of each township contained within the consolidated district. Amendments to the rules shall be filed with the appropriate township clerk on or before their effective date.