Have you looked out the back window of a truck with the tire on the back? It really isn't that bad since the tire mainly blocks the area where you would have to turn your head all the way around anyway. As far as actually backing up, mine hasn't affected me at all. The only thing it does is make it hard to see small cars behind me in the rearview mirror, so I've learned to compensate with the other mirrors and a weaving down the road technique!
