You should be able to adjust it, while in Reverse, then save it. When you put it back in Drive, it should go back.
I just tried it and for some reason after saving it and putting it back in Drive, the mirrors were still pointing down. I switched to a different profile then switched back and it was normal again. I think this is a bug. Now when I put it in Reverse, it did tilt down. When I put it back in Drive, it went back to normal.