I've also been thinking about an air/oil seperator...

Suppose, if you have the room for it, you took a 2oz. tank, and stuffed some of that plastic pot scrubber "wool" into it? That would increase the surface area for the oil mist to cling to (without causing too much backpressure to outward flow ) and hopefully seperate?
The tank would need to be vented of course, but I bet the vented vapors from the crankcase would have a lot less oil in it.

Maybe instead of a 2oz. tank, something like a "Gascolator" as used in the fuel system of full scale A/C could be used...something that could be easily drained?