Add wood around the tab,
Glue some 1/4 inch sticks or other scrap on the ribs so make a surface at least an inch square or so.. Sand it to mach the rib shape. You can even shape them before hand, and then glue them on. You can then either cover around the tab with a small piece as mentioned above. Or cut two small holes in the covering sheet for the wing... that match the distance between the tabs.