I used a wireless one so as not to have to put too many wires in the loom that goes from the trunk to the lid ( a known trouble point ) , but I still needed to run one cable from the trunk to the head unit to activate the auto reverse screen ...
The reverse camera needs to be connected to the reverse wire on one of the rear tail lights , it's the first or second wire in the connector from the top , best to use a voltmeter to check which wire you need , when checking you need to leave the connector , connected to the light , otherwise you won't get a proper reading , due to the canbus system .