In any case where a public officer or employee is absent with leave under the provisions of sections 192.26 to 192.264 and where it is necessary in the public interest to provide for the performance of the duties of the position during the absence, the authority having power to fill a vacancy in the position may appoint a substitute, to be known as acting incumbent, who shall qualify as required for the regular incumbent, shall receive the same compensation as fixed by law, or as may be fixed by proper authority, and shall have all the powers and perform all the duties of the position until the return of the regular incumbent or, if the position is for a fixed term, the period of the unexpired term, whichever occurs earlier. This section does not preclude the making of any other provision for the discharge of the duties of the position which may be otherwise authorized by law.