Tracing the Database Configuration Assistant

I am struggling with DBCA right now so a little tracing is advised.
Note Tracing the Database Configuration Assistant (DBCA) (Doc ID 188134.1) gives a nice suggestion to add these parameters:

-DTRACING.ENABLED=true -DTRACING.LEVEL=2

but it's no elegant solution to edit the shell script in $ORACLE_HOME/bin/dbca

I prefer my new swiss knife for java parameters. A simple environment variable:

_JAVA_OPTIONS= -DTRACING.ENABLED=true -DTRACING.LEVEL=3

This is very useful for any java program. As Oracle has many such programs, there is often use for _JAVA_OPTIONS