Basically it is what it is. There will always be oil coming out of it. Only thing I have seen is a filter/canister system that you have to drain every so often, if it's bad enough that it will soak your undercarriage I would say its time to deal with the issue though.
The crankcase has to have some way to breath. If you just put a ball valve in the tube it will build to much pressure and you will really have an oil leak. You can build somthing out of pvc like the one shown above and drain at oill change.
i remember a brand new cat c15 that slobbered bad. the driver kept complaining about about his "engine oil leak" untill we extended the road draught tube so it vented below the engine. he never complained again (untill one of the guys i worked with accidently lit the interior on fire cutting with a torch under the cab and burnt the truck down in the shop : ) that was a night i will never forget