This is really challenging thing to do without any client-side JS. It would require downloading media (not just little thumbnails) of every post in the current subreddit view. I might make a feature where people can enable (disabled by default) certain features from the preferences which enables them to use features like this which require client-side JS.
Is there any way for a browser plugin to use client-side JS without the site using it? I know this might be a stupid question, but I know very little of extension and frontend development.
That aside, if it isn't too much work to add or support RES features, I would love it and totally use teddit. I (and perhaps some other people here) would even be willing to throw a few bucks your way to help with development/server costs if you open up a donation page.