You've put together the beginnings of a plugin with a lot of potential! Thank you for it!
I have tried integrating it with PageLines' PlatformPro theme. The portfolio pages' content seems to appear in the footer area of its page. Have you seen this type of issue yet? Any advice to retarget the content area with this theme?
1) Download PageLines' PlatformPro theme
2) Download and install your plugin
3) Create a portfolio "main" page and add shortcode to it
4) Create a portfolio page
5) (Re-save permalinks - hope you make this automatic in your next release!)
6) Navigate to newly-created page - you can notice that the content gets thrown into the footer with default styling