That British report mentioning the seats for the loaders made me have a look at the few photos I have of the rear wall. I´ve never been that much into interior details having my hands full with exterior ones. Anyway the first one is from Bovington in the early 90´s and what I think is the point where the seat is anchored to (see arrow), notice that it´s welded;
The second is from the Kubinka vehicle (this time it´s bolted);
I just wished I took more interior photos when I was in Kubinka of the Befehl Tiger I, II and Jagdtiger, now it´s much harder to get inside the vehicles.