I'm in the process of setting up an almost identical setup to what you mention. I was thinking of setting it up in the exact configuration you mention. I was planning to use the inserts on my mixer as direct outs from which to go to the interface, and then send the a stereo mix of the interface back to the mixer. But this is assuming that the insert "trick" will work. Let us know how it goes.

The problem with my mixer though, is that the stereo channels don't have inserts or direct outs...

Chony