since it's fabric, i'd think most any fabric would work. why not try to get a fairly tight but sheer weave of fabric and get some fabric glue (walmart carries both items) and glue a patch on there. it'll show a little when lit, but shouldn't be too bad. if you can get to the inside, patch it there instead. now that i think of it, you maybe could take some clear plastic and make patches with that- which shouldn't show much at all, esp if the glue is transparent. clear nail polish might work as the glue. good luck!