We got a product that uses a low power RTC crystal and a 12Mhz crystal on a 4 layer board. The inner layers are VCC and GND. Should I remove the VCC o r/and GND under any of both crystals? Would be a problem to route or place any component on the oposite side of the board? Currently I am removing the VCC layer under both crystals and leaving the GND layer under the 12Mhz cr ystal to improve shielding but removing under the Low Power RTC Crystal to avoid unwanted capacitance. Is that correct? If yes, considering that there is a GND layer under the 12Mhz crystal, would be a problem to route any si gnal or place components at the oposite layer?