Update 3 May 2020: after a bit of a requests bill spike, I had another look at rclone’s options and the S3 storage classes. You can now directly create backup objects with Intelligent Tiering by setting the backend storage_class, which in theory should be much cheaper for frequent backups. I’ll report back on whether it really is!
I recently tried out a new remote backup approach.
Whether you consider it a success will probably depend on your quantity of files, and how much money you have lying around for month #1.