Dunno if it helps, but perhaps you could use an exterior window-screen
design. You know, for keeping bugs and such out. I redid the screens
in (on?) my old house, and they were a face-frame with a little piece
of molding nailed on to it, which held the screen down.

Nahm did a similar trick with a gazebo, I think it was. His method for
stretching the screens was pretty nifty.

Good luck either way.

-Phil Crow