not sure if possible but think, u know when being chased and u want to see the creatures chasing you, you wouldnt have to turn around u could look in it, but is it possible?
you could try zooming out into third person and then ( if you haven't remaped them ) use the / and * on the numberpad of your keyboard to move the camera to where it is facing you, this would let you have some idea of what might be chasing you
thats not really what i wanted, i am creating a ui for myself and have this one space, and since i really want a rearview miror, it would fit perfect there, i am sure theres a way