Besides, it can be done by adding a folder and hiding it. Then add a zip file containing the images to that folder, lastly add a link to the comments/description to the hidden zip file.
I agree with the keep Plain plain plan. Howsoever, years ago there were some tools and discussions on zip files. Search on "Tzipper" which may make it easy for you to personalize Plain and add the option for viewers to download all the thumbs or slides or originals in one file. Perhaps even you could tempt Rob to tweak this older jaext to current day?