The county boards of two or more contiguous counties may make a written agreement, executed on behalf of the several county boards by the respective chairs and secretaries thereof, whereby the counties may jointly employ a county veterans service officer. The agreement shall specify the compensation to be paid to the county veterans service officer, the amount thereof to be paid by each county, the number of days per month to be worked in each county, the percentage of the total amount of compensation to be paid by each county, the amount of travel and other expenses to be paid by each county, and such other terms and conditions as may be agreed upon by the counties.