Elli and I took transfer functions of the OLTF using common mode B. The optimal gain setting was found to be -14. This results in a UGF of approximately 10.4 kHz while keeping the resonance at 42 kHz below 0 dB (maximum about -2 dB).
At higher gains (-10, -12, -13), the 42 kHz peak was consistently greater than 0 dB.