Ah, cunning... do you mean this post:
https://www.the75andztclub.co.uk/for...4&postcount=27
I think I get the gist... basically, you connect the sensors to the reverse light for power, rather than the ignition live. This means they are 'reset' every time you select reverse. Very cunning.
I might try this on mine, since a sensor has stopped working, and I only have a 'new' sensor to replace it.