You can get them to cut any length you want while there. Try get them to show you the metal connectors to attach it or simply use construction adhesive using a caulk gun. You can glue two pieces of wood with a spot the size of a quarter that a sledgehammer won't compromise. Add your new addtnl pieces of wood and attach your screen to that
A person without a sense of humor is like a wagon without springs-jolted by every pebble in the road.
Beecher, Henry Ward