What about using the gauze they used to use in those big breathing valve cover caps? Or making something along those lines. That or make some kind of P-trap that could let the goo settle and then be drained out. I have seen that sort of stuff in lots of engines I have owned. I had some buick 350s that had a gauze like filter inside the air cleaner. Maybe something like that would work.

\'59 Chevy 1-ton
'72 c-10 (in progress)
The Great Rust(less) Mountain
\'47 Jeep cj2a