Can you serialize custom camera projection matrices?

I need to set up custom camera projections. Upon hitting Play, they are replaced, as if Camera.ResetProjectionMatrix() were invoked. I can override that by storing the custom projection matrices in variables, and assigning them to the cameras in Start() (or some other function), but I'd rather not. Do I have a choice?

The projection matrices are not serialized in the camera class. If you want to store them you need to store it in a public variable in one of your scripts and assign them in Start or Awake.