I wouldn't know why... Every fourstroke I know of has a totally open crankcase ventilation, no lube problems there.

What I WOULD do however, is connect the crankcase vent to a Tee (the horizontal bar of the Tee, to be exact) and connect the other end of that horizontal bar via checkvalve to the fuel tank.
The vertical bar of the Tee can be routed out of the plane any way you see fit.
This will leave the normal crankcase ventilation (which we all know does not harm the engine) unimpaired, but the pressure pulses of the crankcase will end up in the tank and remain there due to the checkvalve.
That should result in a fairly stable tankpressure if you ask me, because it is not the blow-by or ring seepage that generates the tank pressure, but just the breathing action of the crankcase, and any air going to the tank should theoretically originate from outside. Not from the crankcase...