Francesco, the issue isn't width, it is how the holder is held to the camera. The Premo 12 accepts holders with thin lips on each side that fit into grooves on each side of the camera's back. The AAR doesn't have the lips, must be held in place by a spring loaded focusing panel.
Simple test. If the Premoette's focusing panel slides out, you can use an AAR on it. If the Premoette's focusing panel is permanently attached by two springs then you can't.