The oil in the vapor needs something to cling to. Just slowing down the vapor will not let much of the oil settle out. The steel wool can be reused by washing it out in gasoline. I would use course steel wool and even some course scrub pads in the bottom. You could get carried away and do a tri level one... scrub pads in the bottom, course steel wool in the middle and fine steel wool in the top. A screw on lid gallon jug would make it easier to build and service... holes in lid for tube and vents.
If you have a lot of oil in the vent... getting the car dirty I would be concerned about the amount of blowby in the engine and what's wrong with it. If it's a 04 Cat C7 then a different vent system might be necessary as it had problems with excessive oil from the side vent.