I dont think the GPS mount will fit with the 1200 Tobinators.
From the bikes I've seen with the GPS mount, it needs the screen to be fairly upright (vertical) in order for the mount to fit behind the screen (correct me if I'm wrong here).
The Tobinators will actually raise the screen a bit but their raison-d'etre is to enable more tilt whilst not sacrificing the height or the rear edge.
I dont think you'll be able to have the screen upright enough to fit the mount behind.
If any BMWRidersofScotland chaps want to get in touch by email or PM I can arrange a set of test Tobinators to confirm.
Andy