An example on creating split screen / multiple cameras with Phaser through RenderTextures
You can view this example right now in your browser here
If you have Electron installed globally, you can run 'electron .' in the root directory of this example to give it a try.
You can also add this directory to a web server to try it.
lib/game.js and lib/camera.js are fairly heavily commented to explain things as best as I could.