That's essentially how I run the F8 now, with input gain settings on the F8 preset.
Even if not visually monitoring peak levels I'd want to see the meters movement to confirm everything is setup and working correctly.
You'll want to set reasonable mixer levels if you monitor with headphones while recording and/or for trouble shooting. I don't do that while recording, relying on visual confirmation by the meters. But it's also nice to have something reasonably close to a good mix dialed in during recording for playing back from the recorder later (because the recorder remembers), even if doing so simply to audibly identify filesets.