Dynamically render/hide object individually for each camera in scene

I have a scene with 4 character controller Objects (4 capsules equiped with one camera each) and each one has a character animated model attached to. I wanted to hide character 1 from being rendered by camera 1, character 2 by camerz 2, etc.. I know about layers but I don't want to multiply them just for that. Is there another way, like adding a function on a OnPreRender() to not render a specified object ?