relay diagram for rearview camera

i have a dual xdvd8190. i have it all wired up and running for the reverse camera to work. but id like to add on to it to have it also display as a rearview monitor (while not in reverse). i assume i'd need a relay to have it work as both. is it as simple as just wiring a relay standard and using the reverse wire as the trigger and just powering the camera with a +12acc wire all time? is it that easy or is there something im missing? thanks

Power the camera with a switched source other than the reverse wire.  Get 2 diodes, connect the banded ends of each diode to the Reverse wire of the deck.   Now connect one of the non banded ends to the reverse wire coming from the car.  (You already have this wire)  Now connect the other diode to a power source via a switch of your choice.