It is most certainly possible - 9 years ago I was running dual hard drives inside my LCII, if you can do it with an LCII you can definitely do it with an SE/30, or indeed any other Mac with internal SCSI and enough internal space, given that you have a spare 3 connector 50 pin internal SCSI ribbon, and a molex power splitter. My only real concern is that the SE/30, like all other 68ks, is getting old, and I personally would be wary of running dual hard drives or anything else with high power consumption unless you have an auxuillary power supply setup similar to JDW's.