I'd say these guys are on the money with revising your springs/rates.

If you're experiencing a harsh ride on rough roads, it's more likely your springs and shocks, and generally coilovers such as yours are far less than ideal for those outback roads.

Keep in mind that a sway bar, or anti roll bar doesn't have much affect on ride quality when you aren't cornering, as it can freely pivot up and down with the suspension. I would think the ideal setup in your case would be some compliant springs and shocks (ideally some kind of progressive springs) combined with some decent size sway bars.

Maybe consider OEM ITR suspension or Koni yellows with your choice of aftermarket springs.