There is no 'safe' way to run a harness without a cage. Bolting your head in so it can't move, but not preventing your roof from being able to crush towards your head means you're more likely to be hurt in a rollover than wearing stock belts.
If you're wanting to see SCCA rules, go to scca.org - what the majority of people have on their cars are not scca qualified.
Originally posted by indoubt
well its not only the rules, its if you get into an accident, its to make sure you get out of the car SAFE.