The board may provide such covenants as it may deem necessary to secure and guarantee the payment of the principal of and interest on such bonds, including but not limited to covenants to create reserve accounts and to authorize the deposit of certain moneys therein for the purpose of securing and guaranteeing the payment of such principal and interest, to appoint a state or national bank or trust company as trustee for the bondholders to hold, invest and disburse moneys set aside and pledged to pay and guarantee the payment of such bonds and/or as a trustee for safeguarding the disbursing of the proceeds of the sale of such bonds, to fix such powers and duties of such trustee or trustees as may be found necessary to carry out the purpose of this act, and to make any and all other covenants not inconsistent with the provisions of this act which in the judgment of the board will increase the marketability of such bonds. The board may also provide that revenue bonds payable out of the same source or sources may be later issued on a parity with any revenue bonds being issued and sold. The provisions of this act and any resolution or resolutions providing for the authorization, issuance and sale of such bonds shall constitute a contract with the holders of such bonds and the provisions thereof shall be enforceable by any owner or holder of such bonds by any appropriate suit, action or proceeding in any court of competent jurisdiction.