I have an old set of finned edelbrock aluminum covers on my truck and to keep the oil from going out the K&N valve cover breather I built an extension out of steel tubing that raises the breather up about 6" off the top of the cover.

It looks sorta like a circletrack or trans-am setup....
http://www.sallee-chevrolet.com/ChevySmallBlockV8s/images/88958602.jpg

I think you can buy pcv valves that have shields built around them that function like a baffle.