[David Iglesias]

Of course, now I'm a bit nervous that I'll get some server mismatch when I go online with the car, because I've modified it (even if it was only the driver graphics). 

That's what I thought when I read the solution, I want to think that every change made on the car will throw a mismatch error on the server.

I faced this helmet problem before and what I usually do is to use the Onboard Setting app to move the seat position or I just move my head back and I recenter the VR view, so when I come back to my natural position the helmet is behind the camera.
Please let us know if the Rafael's solution works online.