Looking to switch scene camera

First, CONGRATS!

Turning on and off your default render layer on the camera is probably the best way to do this. To start though, you need both your cameras rendering. In your scene, create a second camera by selecting Add New -> Camera in the Objects Window. Make sure the new camera's Input field is set to Device Camera Texture. Then, in your Window window, select Add New -> Texture -> From Camera and select your newly added camera. Finally, select the original camera and set its input field to this newly created output camera texture. This will create a rendering chain so that everything both cameras see will be rendered. 

Next, I created a simple script that enables and disables the default render layer based on the toggle checkbox in the inspector. Bind this to Initialized, link the two cameras and each time you press the toggle checkbox you should see it reflected in the preview window. 

// -----JS CODE-----
// @input Component.Camera cameraA
// @input Component.Camera cameraB
// @input bool toggle

if( !script.toggle ) {
 removeAllRenderLayers( script.cameraA );
 removeAllRenderLayers( script.cameraB );
 script.cameraA.addRenderLayer( 0 );
}
else {
 removeAllRenderLayers( script.cameraA );
 removeAllRenderLayers( script.cameraB );
 script.cameraB.addRenderLayer( 0 );
}

function removeAllRenderLayers( camera )
{
 var renderLayers = camera.getAllRenderLayers();
 for( var i = 0; i < renderLayers.length; i++ ){
 camera.removeRenderLayer( i );
 }
}

Here's a demo: