The solution I'm pursuing is to use the Bozure Isolator board -- I have one on order now:
The Bozure ISO-1 runs on 18v, and this version of the Rane quite conveniently has 18v rails and a beefy internal supply. There is plenty of space for all 8 Blue Velvets once the channel faders, crossfader, and CF switch are gone (as they are in mine), but I'll probably have to put the isolator board itself in its own chassis.
My Rane was bought broken with no top and bottom panels, so I'm having to come up with a chassis solution anyway. That turns out to be an advantage for this particular application.