Some of the issues come from the BMW lights. LCI has pulse width modulated (PWM) bulb signals and preLCI is analog signals (OV, 12V). I'm sure there is an analog reverse signal on the LCI system somewhere. From the reverse light switch at the gearbox to the PDC module to the trailer module... Somewhere.
The easiest signal for me would be a digital signal of 0 or 1 coming from the IBus for activation.
