Looking into a mirror is usually a bad idea. Your cervical spine is a very common place for injury and very lethal. Fortunately, not much pressure should be on it (why you don't have the bar on your neck), but it's still better for you if you keep the back of your ears even with your shoulders. That means looking slightly down.
As an EMT we ALWAYS keep the cervical spine neutral when we are boarding someone. That’s simply because the body likes to be at its natural position. It’s pretty logical you’d be in that position lifting 2x your bw as well.
