Oracle RMAN can access tape devices only through a media manager. Sorry, don't know LTFS, but have you looked into Oracle Secure Backup or Oracle Secure Backup Express? The later, if I remember correctly, is available for free.
When using Oracle Secure Backup with RMAN to back up and recover databases and files to and from tape, no third-party tape management software is required. Oracle Secure Backup provides the media management layer needed to use tape storage with RMAN. It supports every major tape drive and tape library in SAN, Gigabit Ethernet (GbE), and SCSI environments using standard tape formats.
I played around with it some time ago, trying with virtual tape devices. Perhaps you find some useful info:
we are using EBS R12.1.3.which version we suppose to use?