You don't have top get too fancy with the screens. An 18" square of 1/2"
hardware cloth will stay there if you fold it up carefully, wear gloves. A 3'
square from the hardware store makes 4.
Mine survived Charley, Frances and Jeane.
BTW the roof rat (rattus rattus) thing is real. I have lots of citrus and we
had our bout with the rats.
The real problem is, if one gets in, he will eat a hole to get out, then his
buddies will come and go until you find and patch the hole.