I'm still using P6. I think the ability to add extra cameras came in with either P7 or P8, so I'm not talking from personal experience with those versions. However if your Poser version allows you to create new cameras, this should work.

Download and install "MinFig" from my free stuff. In Poser, create and set up the new cameras as desired. Parent them to MinFig, then save MinFig back to the Figures palette with a new name, say "CameraSet-01". The next time you load ""CameraSet-01", the cameras should load with it.