Auto-save custom post type page from the front-end?

I currently have a setup that allows admins to add content to a given custom post type page from the front-end. I'd like to allow them to select various theme, color options, drag-drop layout choices, etc. for their page as well. I am able to figure out (for the most part at least :wink: how to accomplish the edits/changes, but not the auto-saving aspect.

How do I allow the tweaks from the admins to be auto-saved?