Is there a way to see in the camera window exactly what is going to be rendered by Vray? Just the outline of the frame would be great. I know there is a setting in vray to match the viewport. However, I want to set a certain frame size and ratio of height to width and then view that in Rhino. 
you’re looking for the safe frame, probably ?
Enable it from Rhino’s viewport properties
That’s it, thanks.