You'll need to read the GCR closely on this, and it's in the midst of a wording change, so it might be cloudy. My info, after talking with members of the CRB, is that their intent with the rule, is to allow IT cars the ability to gut the driver and the pass door IF "NASCAR" bars are installed.
Now, SCCAs definition of a NASCAR door bar setup is not what many people picture. It merely means that the door bar setup must intrude into the door cavity. In other words, your door bars must requre your door to be cut if it is to shut. Now, the rule doesn't say how MUCH the intrustion must be, nor the number of bars, if any, required over the minimum. So, in my case, I decided it made sense to gut my passenger door, and to install the NASCAR setup. But the definition is minimal, so it's legal, in my opinion, to configure an X bar setup that intrudes into the door cavity. My feeling was that, for the right side of the car, that was smarter, and safer.
YMMV.