If your wife has a bad back then the reversing issues will be the very least of your problems. The XC40 has the worst suspension of any car I can remember owning. It bounces all over the place on uneven roads and the lateral wobbling does my back in no end.
Not noticed this at all actually. Was quite impressed with ride quality, especially in front seats when we test drove the car a couple of times before committing.
Rear seats I am less impressed with but we’ve had the car for a week and so far so good on the whole.