I can't speak to RDS specifically, but if you can get RDS into either S3 or Glacier, then there is an easy path to rsync.net: rclone. The ssh access is not to

I can't speak to RDS specifically, but if you can get RDS into either S3 or Glacier, then there is an easy path to rsync.net: rclone. The ssh access is not to Amazon, or S3 or RDS, etc. - you run the rclone command at rsync.net, over ssh: ssh user@rsync.net rclone s3:/some/bucket local/rsync.net/dir