I had a similar problem on a car I autocrossed and ran on road courses. I finally pried off the cap and attached a long hose that I ran into a catch can in the trunk.
The 9'' ford rear in my vega did that , I plugged the vent and tapped the oil fill plug and ran a hose , nintied up to above the rear end , took care of it , but was a pain in the drain to check the oil level.
