if life saver looks dont work for you then there is nothing wrong with using your mirrors. i dont have a lot ov flexibility in my back and cant rotate to look over my shoulder, so i use a lot of mirror observations instead. and the lifesaver is really just to see whats next to me, not behind. i find sports bikes are a nightmare for lifesavers as your leant forward which further impedes my rotation. for the test, as long as it looks like your using lifesavers then i would say you'll be ok. see what your instructer reccomends as i am sure your not alone.