Reversing in the dunes, I trust my own judgement than anything shown on the mirror, screen or sensors.
Best is to roll down the window to have a good shoulder view on either side and keep reverse with partial eyes on rearview mirrors or screen. Secondly while reversing in dunes, I pay attention to the car level more, that means if im dipping on left I counter steer on right to stay on flat rather than dropping in some unseen sand pocket or dune.
In the night drive in the desert, it's a whole different game. Don't reverse as far as possible, if you have to step out and see first and then decide how many exact meters of the reverse is needed.