Instead of an incremental backup where messages continually add up, can Gmail Backup be set up as a mirror so that deleted messages on Gmail are not retained by Gmail Backup?

Fox example, I backup Gmail today and have Email X with a 5MB attachment in my inbox. In a few days, I delete it from my Gmail inbox because I don't want it anymore. Now Email X (and its attachment) is still in the Gmail Backup directory. If I understand the documentation correctly, Gmail Backup runs an incremental backup which means that the next time I backup, Email X will still be kept in the backup directory instead of deleted to mirror what my Gmail account actually has in it at the time I of the newest backup.

Basically, I don't want stuff I've deleted in Gmail sucking up room in the backup directory. Can this be done without manually deleting the trashed emails from the backup directory?