I also angle my electric mirrors down to check where the white line is when parking, as I think that it is safer to reverse into a parking space, so that you don't have to reverse out. For a long time I complained bitterly about the extremely poor visibility in my car, a 2 seater convertible, because the roof blocked of so much of my view of the road. It's only since I have found it easier to turn my head that I have realised that really the majority of the problem was that I couldn't move very well, so I couldn't lean forwards to see better, or look out of the back window. I even considered trading my car in for a different model. I don't know why it never occured to me that the problems I was having were associated with the radiotherapy. I lost a great deal of confidence in myself, and in my driving ability, which is only slowly returning.
My husband is looking at fitting aspheric glass for my mirrors. Aspheric glass is curved at the outside edge of the mirror, thereby extending the field of vision. It is worth asking your garage if they do this glass for your car. It is not available for mine, but as my husband works in the industry he is hoping to be able to put together something to fit my car.