Hi!
Well, after some experimenting I might have found a possible solution, where you won’t need to change anything in the plugin files.
Simply use this custom CSS and the vertical layout:
[html].asp_image {
width: 100% !important;
height: 200px !important;
}[/html]
It will force 100% width for the image with a 200px height (of course you can change that). This resulted in something like: http://i.imgur.com/b7MHvGd.png
I hope it helps!