Maya Camera Resolution Gate -- Framing for Crop in Post


I have a problem where I need to render an image at an aspect ratio of 1.77, which will then be cropped down to 1.0 in post. I am looking for native solutions within maya that would help me visualize this crop similar to a resolution gate?

Changing my resolution width in render settings seems to change the height of the resolution gate mask – instead of the width?

Any help or plugin references regarding this problem would be greatly appreciated!

Using Maya2018 Rendering with Vray Next