The board of county commissioners, by a suitable order duly made and recorded in the office of the county recorder, may, when they deem it advisable, provide for payment of interest on such county bonds for a period of not to exceed five (5) years out of the proceeds of the sale of such bonds and in that event no assessments need be collected for the payment of such interest charges until the expiration of said period of not to exceed five (5) years, and in such event the amount of the estimates, and the liens, instalments to be paid, and bonds to be issued and sold, shall be increased to a sufficient extent to provide for such funding of interest and to provide the funds required for such interest payments as well as for construction purposes and for payment of the amounts due or to become due on contracts entered into in pursuance hereof. But such order for the payment of interest for not to exceed five (5) years out of the proceeds of the sale of bonds shall be conditional upon there being available in the county treasury a sufficient amount of money from the proceeds of such bond sales to complete the construction of the proposed work, in addition to the amounts to be paid out for such interest payments and should the funds available in the county treasury for the sale of such bonds be insufficient to make such interest payments, and also complete the proposed construction and the payments of the county’s obligations on its contract or contracts in connection with such project, then, notwithstanding any such order or orders for payment of interest out of the proceeds of the sale of bonds, the county officers shall proceed to collect by taxation and the enforcement of liens as provided in this chapter, the funds necessary to make interest payments and shall use the funds derived from the sale of bonds for the purpose of completing the project and completing payment of the county’s contract obligations insofar as the proceeds of the sale of bonds may be required for such purpose.