This is what I've done for my aging father...in each of the window's mesh I've cut a vertical slit approx. 1ft in length (the "main window" has 2..about 4 inches apart). At the ends of the slits I've sewn the meshing together to prevent further tearing. This works great since the meshing along the slit "rolls back" giving about a 3-4" opening. I know this doesn't sound like much of an opening, but when your arrowtip, or rifle bore, is in the opening you fov is almost unhampered. At 15yds the slits are slightly noticable, but it's better than a gaping black hole/spot.
That's my 2 cents.