Firewire and SCSI cards, not enough slots

Hello
I've got My G5 with Dual 2.5ghz processor, an Atto ExpressPCI UL4D card and a firewire 800 card. The computer came with the SCSI card installed, but (unknown to me) we inherited, from the guy who used to do all the commercials for us, a Lacie 1 terabyte firewire drive. I was (and still am) working with standard def footage, so I saw no need for the SCSI card. So I bought another 1 tb drive, a firewire 800 card and life's been grand. I'm now looking into buying a DLT tape backup system that only uses SCSI. BUT, all of my slots are filled on my G5. One with a graphics card (which takes up 2 slots), the firewire card and the last one for my Decklink Extreme video card.
SO, am I hosed or what? I've seen both on apple's website and here that firewire to scsi adaptors are unreliable/not recommended. Is there another backup system that will work that could utilize firewire?

tVs