It could be done, as Shambles says, but just be aware that doing so might keep the Body Control Module awake. The car goes to "sleep" (i.e. all electrical systems shut down) when you lock it, and sometimes playing with things like that can make the BCM stay awake, which can run the battery flat. Also, the only way to stop the radio if you modified it like that would be to turn it off and then press the DARK button to make the screen go off. The radio would still be powered up though and even if it doesn't bother the BCM it will use more power than if it was completely off us normal.
If you do it and then something starts acting strangely, that will probably be the cause. Worst-case scenario, you can always change it back.