Reversing camera feed from parking sensors

[Loonytoon]

Good evening all.
Fitting reversing camera to my 65 plate limited custom.
Want to take the switch feed from parking sensors not reverse lights so camera is on while maneuvering, not just when reverse engaged, and can be turned on via the parking sensor switch on dash.
Any one have any ideas where I can pick a feed up from?
Thanks in advance.
Rob