GPS

[mwaters]

Try to reduce the GPS bus speed down.
Baudrate from 115200 to 57600 bits.

Reducing the baudrate I'd not expect to help anything regarding the reception of GPS satellites. This baudrate has effect only to the two signal lines GPS_RX and GPS_TX on the main PCB between the GPS ASIC and the micro controller. Not receiving satelleites is more a problem located on the side of the antenna / antenna cable / GPS-IN / RF_IN of the GPS ASIC.

I agree, even though the frequency on the GPS feedline can be up to 30 MHz.

A lower baud rate might help if you had a very long RS-232 serial line. But your GPS coax is not that long.