How to designate a viewport for one camera? If I have multiple cameras in a scene, I would like to choose a 3D view and dedicate a camera to it. 

I would like a single 3D view when I choose camera view, Num+0, it will ignore my other camera selections and always show the view of 1 specific camera no matter what. Even if I use that 3D view for other view modes modes it will always come back to the same camera for camera view. Even when animating to switch cameras won't affect the 3D view. Like a monitor directly connected to that camera.

How do I set that up?
Blender only allows one active camera in a scene and numpad 0 moves the view to the active camera, so you can't setup a different camera view for each viewport.

You can setup as many viewports as you want and you don't have to be viewing from a camera in each viewport. Blender includes an addon called stored views which gives you a way to bookmark multiple viewport locations, this can provide an easy way to set a viewport back to a desired viewing location, similar to what you would get from a camera.