No one I've met uses the WB for bowfishing, but it looks like it would work great.
Just use the AMS safety slides with it so the line never comes back past the rest.

There is a Bowfishing WB that is supposed to have stiffer bristles than the original. They should last pretty long without fletching to wear on them.

I've also heard you can put hairspray on the bristles to stiffen them once they get a bit broken in.