How to display Full width Featured Image as background for Pop Up Pro

I tried adding an image in the featured area but the image gets cut off at 280x350 when my image is 700x350.

So after playing with the plugin, when not enabling responsive design and setting the width to 700 and height to 350 i have the following questions.

1. How do I make the featured image extend fully across the pop up.
2. Will this cause some overlapping issues (will z-indexing need to be added to the css?)

Side note, I've made some changes to the existing css and was able to make it work that way, but I don't want to have to keep adding the custom css every time I make a new pop up. Sometimes I may want a repeating pattern that extends all the way across. This is a must as it doesn't make any sense not to have this feature. Am I the only one thinking like this. I know I could make a full image as the pop up ad with a pattern and make it look flawless. This plugin needs more customization on the featured image. Perhaps allowing to repeat , alignment, and set to cover so it can play nice with responsive features.