Hey JustinSA -
There is a way to change and lock the main viewport to a particular camera actor. (See my steps below) There is also a way to up the size of the preview window in the Editor Preferences under Level Editor >> Viewport >> Look and Feel >> “Camera Preview Size”, by default it is set to 5.0. Both options might be helpful.
Hope this helps you out,
Eric Ketchum
To Change and Lock the Main Viewport to a Camera Actor:
Right-Click the CameraActor and select “Snap View to Actor”
With the Viewport now snapped to the camera actor, click on the dropdown menu at the upper left of the viewport and select Lock Viewport to Actor >> Lock to [Name of Camera Actor]
The main viewport will now control and show the view from your camera actor including FOV (hence the black bars) and show a padlock icon in the upper left.
To unlock the viewport, simply click on the dropdown menu at the upper left of the viewport and select Lock Viewport to Actor >> Unlock from [Name of Camera Actor]
