Here's a quick first draft of a mobile article preview gadget: https://meta.wikimedia.org/wiki/User:Brion_VIBBER/mobile-sidebar.js
This shows the currently viewed page on the mobile view in an <iframe> sidebar, and captures link navigation within the iframe to navigate on the desktop window as well.
To enable add to your ~/common.js: mw.loader.load(' https://meta.wikimedia.org/w/index.php?action=raw&title=User:Brion_VIBBE...' );
Todo: * add an on/off switch * fix width to adjust for scroll bar if visible * make a couple common sizes selectable instead of just 320x480? * figure out how to apply this to edit previews? (is this even feasible without API changes?) * fix edge cases with the navigation detection * pretty it up * enable as a gadget on some major sites
-- brion