Hi.
It won't be easy, because our module uses default image from K2 item, this same for default articles.
But you can try to create a special XML (every time) with different image link which can be used in NSP GK5 as a source of content.
Second solution could it be, a modification of image engine from K2 - to use/generate square or whatever shape images. Than you can use it in module without creating a second version of each image. Hire php developer it should be easy for them.
But as you see it's custom job - not standard support question.