I have PDC but that isn't the issue, the issue is seeing behind you which the head rests block maybe 30% or more of the rear vis.
I will take some pics once I head back to Ohio again to drive the car down.
I just got a new Outback and first thing I did I pulled the rear head rests on it too because it too blocks the rear vis.
The headrests just slide in and out using the two bars the same ones you use in the older E36s, there are a couple of detents and that is it. Pull hard up and it will come up and out. To reinstall just stick the two bars back into the insert holes and push down until you bottom out.
Backing up for me was not the issue it was driving and being able to see behind me.
Hope this makes sense.
If you see post 13 here you can see the bars I am talking about