Voucher id len increase

Increasing len of the voucher id field from 8 to 12 char.  A client of mine is asking for recommendations on how to deal with the voucher id field size limitation.  One option is to tap into the archival process, but I recall this question being asked numerously to oracle and the response was that development may review at a later time.  That was 2013.  What is the leading practice when dealing with this situation, especially for large volume shops that process thousands of daily transactions?