[mzs]

Thank you for sharing the story.

I too think that being buckled-in is the most important, but a 4 or 5 point harness will just not work in a street car. Maybe my best advice is for you to read the relevant sections in the SCCA handbook. Forget about the cage, assume just a cross bar and harness. You will see that it makes it impossible to have the harness at a safe orientation for the driver yet allow a rear passenger. Also when you add the cross bar as it also required, it is now unsafe for a rear passenger.

Further any car with a cage has other compromises and some of those reasons for a cage are for things like being able to quickly jack the car up and rigidity (not just safety) but limits how people can enter and exit for example.

A harness is just not a good fit for a street car. The three point seat belt is an excellent compromise.