This, JDM wagon pinks, or coilover are the correct way to do things. Spaces change the point where the springs block out vs the bump stops (which are mounted to the body) engage. This can cause the springs to block out before the bump stops have fully compressed, which is not good. I had the rear spring mount get knocked off a set of shocks due to this, with only 3/8in spacers.
If ride quality is a priority, you can get coil-over sleves for the normal rear shocks. If you run a 9-10in long spring you shouldn't run into any bump travel limitations.