Mounting a filter sock?

[gregzz4]

Pat 3" is not an issue, you'll be fine with whatever you come up with
Just do yourself a favor and make it as easy to service as you can

The baffle after my filter sock tray is 1/4" below the trim and water has never touched the it. I once used mesh socks that plugged daily but the trim stayed dry.
I use felt socks. They don't plug and are 100% submerged