The board of hospital trustees may also as part of their compensation either through purchase of plans or through plans of self-insurance provide for suitable retirement, health, life insurance, and employment insurance plans for all hospital administrators and employees, and the employer’s cost of such plans shall be paid by the treasurer of the board of hospital trustees in the same manner as other expenses of the hospital are paid; provided that the board of hospital trustees shall be taken and considered as a “political subdivision” as the term is defined in section 70.600 for the purposes of sections 70.600 to 70.755.