Ballistic glass is extremely heavy, typically consisting of multiple layers of glass and polycarbonate along with a TPU between each layer. Windows on ballistic proof vehicles I have built in past, were over 1-inch thick and so heavy the side glass required special motors and mechanics to lift...
I suspect this concept will have very limited use. I say this because, as everyone who has ever driven a vehicle having a rear glass or rear hatch open in this manner will attest to, the excessive amount of exhaust and road debris/dirt which enters through an open rear window/hatch can quickly...
I'm quite sure within the Crash Monitoring System and/or Vehicle Dynamic controls, there is an inclinometer who's value could be displayed on either screen via a multi-color bar graph including digital values