and another way
I made a simple action out of this:1:
make an invert adjustment layer2:
in the blending options of this layer uncheck the R channel and drag the "Blend if Gray" this Layer the whites at 255 and blacks to 0 (I use 2 to have some buffer left)
At this way you have red in overexposures and turquoise in underexposure just like in Lightroom.
I simple love to trigger this solution via an action and itīs on top of my Layerstack most of the time.