eSATA mod-- need adapter, cables?

My MacPro 1,1 has finally died. My main storage is an eSATA RAID, and I know there are Thunderbolt adapters, but they're expensive. Have read much of eSATA mods on earlier mini's, some seemed to require removing optical drives, etc.

Does anyone know if, with a single boot drive installed, there is a *spare* internal SATA connector, to which I can connect a SATA to eSATA cable, find some way to route it outside the case, strain-relieve, etc., and connect to my eSATA RAID? Or is the iFixit two-drive adapter needed, even though I'm not installing a second drive inside the case?

Thanks.