The board will accept in lieu of other wage information a stipulated wage agreement executed by the injured employee and the insurance carrier which establishes by mutual agreement an average weekly wage and a weekly compensation rate on a standard form approved by the board. Such stipulation may be considered by the Industrial Accident Board, along with any other evidence concerning the wage rate, but it will not necessarily be binding upon the board. No action by the board on the claim shall be taken as formal approval of such stipulation, and the same shall be regarded only as an informal waiver of proof for purposes of the hearing before the board.