#10 [Layout][Schematics] Microphones on S2 are facing the case

Microphones placed on S2 (upper surface of LOWER board) will face a case rather than a spacerframe similar to a sim card holder on the picture below (http://neo900.org/stuff/papers/simsw.pdf). Design however assumed that they will face a non-vanila custom-crafted spacerframe (which is also depicted). This will make orifice drilling required. Maybe there are other options?