Auxiliary Dash Power Button Option

I have been thinking about the possibility of ever needing the dash to be powered without the car's Ignition switch turned on say in the event of a car show or something. My thought is that one of the Lower Console buttons could be rigged to supply power to the dash that would bypass the need for the Ignition to be turned on as that would be very impractical during a car show. So this is what I have come up with in the way of a wiring diagram to do that. Basically in my case the coloured lighted switches on my Lower Console use a Negative or Ground connection so the other side of the magnetic could of a SPST Relay would connect to 12V, this then would activate the Relay switch which would allow the connection to 12V to flow to the dash electronics effectively bypassing the Ignition Switch.