Perhaps HKese are really rich or else, why you need it in the first place? Are you driving an oversized vehicle? Afterall, when you put your vehicle in reverse, you should have turn your head and look at the back (NOT via mirror) so that you have a much better view. This works for SUV and mini-van, let alone sedan.
For parking sensor, I should warn you that do not relay too much as it have a lot of blind spot.
Perhaps HKese are really rich or else, why you need it in the first place? Are you driving an oversized vehicle? Afterall, when you put your vehicle in reverse, you should have turn your head ...