There's no microphone near my church's baptismal font.
But your pastor doesn't get in the water, does he (or she)? As I recall you are PCUSA, and dunking, while permitted, is exceedingly rare in most Presbyterian churches. Does the preacher use a wireless mike?
Most churches I've seen with a baptismal pool have either had the mike aimed in from the front or dropped from above. That being said, neither arrangement should require the preacher to adjust it. If the signal isn't loud enough, the sound guy should be able to provide sufficient boost.