So, the reverse sensor in the multi is driving me crazy... as soon as you are in reverse its a constant tone, from nothing behind right up until you slam the bumper into a wall. I hate it! is there an easy way to disable it? or is it possible to take its power feed and use it to power a reversing camera (just to make it easy to line up on a trailer)?

You've got a short in the wiring for one or more of the sensors, or a piece of crud stuck on one of them. Have a listen to them close up with it in reverse, ignition on 'MAR'. The sensor that isn't clicking is probably the one with a problem.

The speaker and connections are in the rear wing void where the jack and tools are kept, but below the rear light cluster. NS cover in the boot.