Rick's idea is fine and I solved the same problem in a similar way with different material.
Get a brass thread "scrubbie" from the supermarket, the kind used to scrub old sinks. Gently pull the fibers apart so they're not so dense and crankcase pressure can vent through them. Put a loose zip tie through it from top to bottom to use as a "handle" so you can remove easily to add
oil.
The pressure vents but the
oil splash is trapped by the brass. Never gets dirty either.
Good luck,