As expected, my first concept idea rarely looks as good when modelled in CAD. I'm not concerned about the part that goes around my head at the moment. I'm more trying to think of a good design for the top of the cap.

The cap thickness is 25mm and the tallest square is another 50mm ontop. At that point, I might as well mount the screens vertially. At least then I'd also have space for the decollimating optics too.