Well, the stock mirrors on my 1989 4Runner can fold relatively flat. When folded, I don't think they hang out further than the farthest part of the door. I don't see much point in going any flatter than this. If you have an object this close, you are probably going to take out any mirror and/or some body parts.

I will admit that it is nice to be able to just pop them back into position and not have to readjust them.