Is it possible to automatically export a specific Collection to a backed-up location?

You can create a Hard Drive Smart Publish Service and use this Plugin to automatically run the Publish at a specifiec time.

http://regex.info/blog/lightroom-goodies/bag-o-goodies#publish-at

My entire workflow is based on keywords and smart collections!

Just give a group of images an odd keyword like "AWSbackup" and then set a smart collection with a rule for that keyword.  I believe the keyword rule option is located under the "Other Metadata".

I've never had any trouble keeping metadata with photos when they are exported, unless specifically checking the box to strip metadata.  Are you finding the data is missing?

Let us know how it turns out.

In Lightroom Classic, you need to back up the original photos, and the catalog file. Making daily or weekly backups of your edited photos in a (Smart) Collection is not necessary (and in my opinion, this is the wrong way to go), it affords little protection. (And I ask, why are you not making backups of all of your photos?)

I would recommend getting true backup software that can backup your original photos and catalog file automatically, you can set it to different configurations, such as making backups of only files that have changed or are new, for example, on a daily basis, and once a month make backups of everything.

Create a special tag (keyword) and apply that to those images you want to export. Then create a smart collection that searches for this keyword. Lightroom can't automatically export images at a certain time, however. You have to manually select them and export them. It requires frequently looking for new, not yet exported, images however and that is a PITA.

I would suggest not to use export for this reason, but to create a publishing service to the backup disk. It still means you have to remember to click Publish every day, but Lightroom will keep track of what's new, what's changed and what's already published and publish accordingly. You can choose in what file format you publish, a finished RGB file like tiff or jpeg, or DNG with edits in metadata for example. Capture dates will always be retained, but the file creation date will obviously the date this new file was created.