I think if you want to incorporate any complex boarding scheme, such as back windows first, back aisles next, middle windows, middle aisles, front windows, front aisles... you would have to implement a Zone system. Unlike some airlines, you would probably want several zones, not just three or four. They also need to print the zone in huge type. People have no clue what's on their boarding pass, and certainly have no clue about window versus aisle seats.

A zone system lets the computer determine the order, rather than the passenger try to determine their order based on what the GA announces. It also creates consistency for the GA as well... one thinks the "back" of the plane is row 20 and above, another row 18, another row 15... all over the board.