I did Saurfang with 3 dps once when we had some players dc.
Other than Saurfang the possibilities are rather limited. Not impossible, impossible is nothing. And even a stationary fight as Saurfang requires you do be very carefull with the bloodbeasts. (Because being hit by them gives saurfang his stacks)

But as the topic has hardcore mindset in the title: On a single player I do more dps manually than macroed, and having to move 3 players to move out of stuff makes 3 players not doing dps.

Eventually with enough gear in the raid fights will get easier and easier, thus making boxing them more viable. But at this moment in time (progress in my guild, my situation) it's just not viable.

Now currently I do run Togc with 4 dps or 1 healer and 3 dps. But that's farm raids and even then only to fill empty raidspots.