Where to place the speakers?

[ogs]

The corner is not a very good spot as the other Phantom would 'see' just the wall behind and not a side wall or a corner. You'd have an L/R imbalance that is difficult to fix. The opposite part is probably better as you'd have better symmetry with the wall to the sleeping room on one side and the outer wall to the balcony on the other. The sleeping room wall should maybe have double plating and extra insulation for stiffness and damping...