Running a breather set up out from behind the air filter will do the same thing as venting the out tank, correct? I think that will be my approach. Would you recommend running a small filter or a vented catch can?
Nope. It might solve the same issue, but it is venting a different area of the power train. The oem breather vents the head/rocker box area. The cam chest vents to the heads through the push rod tubes, and the crank case vents to the cam chest through a vent passage which is sized to insure that it also vents through the bearings, so as to lube them. The MoCo changed this with one of the oil pump upgrades, to make the pump suck through the crank bearing, to reduce the amount of oil left in the crankcase. The oil pan vents to the cam chest through a bulkhead passage.
The design of the internal breathers allows vapour to vent out of the head area, but it does not allow it to return. So the motor pushes pressure out as the pistons go down, then draws a vacuum as the pistons go up. The breather unit also contains an oil separator, and that is where the issue is. On Twin cams you can open the drain holes up and correct the issue on an other wise sound engine. Not sure if that is the case on the M8, it uses a different breather asm.
By venting the oil pan you will indirectly lesson the pressure inside of the motor. But some of the bearings are oiled because of the pressure in the motor and the way it is relieved through the motor. And venting the pan may change some of that. Redirecting the breather vent at the air box does not alter the pressures inside of the engine, it just directs what come out away from the intake.
Past that, redirecting at the the breather costs < $10. How much does that oil cap thing cost? And how much effort does it add to checking the oil level?
Done properly, you have to look real close to see that a scooter has a breather bypass done to it. There is no hiding that oil cap plumbing.
This scooter has redirected breathers, can you find the hoses?