We followed your description to follow the cliffline to meet the base jumpers track, and took that trail to the tourist track up the pass.
From mirrorball we hiked along the cliff past a vertical swamp and small pool for ~30m, dropped down to skirt around the base of the cliff between critical mass and smarkland, and then hiked back up to the cliffline near smarkland (small drop down and up. 20m vertical or so). Up to here there was a very faint trail. Then we dropped down a rocky gully to skirt around walls lookdown, and then hiked back up the next gully on the far side of walls lookdown (much larger down and up. 50-60m?). I think we found the base landing spot here near the cliff base, but it was only a small gap between trees. The bush in the gap was all knocked over in the direction a base jumper would enter and there was a bunch of human trash around (old socks, plastic wrappers, a broken iphone, etc, which we packed out), but it was a very small entry with little room for error. So we may have missed the main landing.
From here there was a network of faint trails but nothing obvious. We bushbashed through vines and scrub down and around the base of Rigby Hill and found a big and obvious trail immediately at the base of the cliff. This was the basejumper's track and we easily took that to the tourist track and out.
This hike from Mirroball to the car took 2 hours and was much easier than our previous experience dropping all the way down to the river.