I think I've got a viable ergonomic layout that also looks good aesthetically, but now I need to think of a slightly different mounting solution.

The original plan was to mount Tetent like so:

(The above is a slightly older concept design, with the Tetent Turntable on the right)

The issue is that, unless the bottom of the desk is the same height as my arm in the shape L, my wrist performs an uncomfortable angle and using the thumb buttons is even more uncomfortable. I'm going to have to find a way to mount the keyboard at angles off axis to the desk / table. This may mean I'd have to move the battery somewhere else.