How can i add a second camera?

I know there is multi control for cars but I want the other car to have its own camera, (split screen) I know this is possible but how do I do that? Do I have to modify the lua? modify the map.json? What file should I start to modify? core files for Tourqe 3D or BeamNG or both? point me in the right direction and I'll do the rest thanks.

 

I believe this isn't possible without having access to the rendering code.