County commissioners shall receive an annual salary to be fixed by the county board, which salary is in full for all duties performed in any capacity as a member of the county board. In addition, the county commissioners of counties organized under Division 2-4 shall not receive an annual salary that is greater than the annual salary paid to the county clerk of that county. County commissioners are also entitled to travel and expense allowances as determined by the county board. All are to be paid out of the county treasury.
     No per diem or travel or other expenses for transacting county business, other than board meetings, may be paid except upon the filing with the county board of a report stating the nature of such business. Such report shall appear on the minutes of the meeting of the county board at which such per diem and expenses are approved.