You may reduce it slightly if you completely re-did the wiring harness, but then again, you may not.

The noise reduces (it will still be there but a lot quieter) when you touch the strings as you are connecting your body directly to ground. This stops it acting like an aerial and channelling noise toward the pickups, and also helps your body act like a ground plane that shields the guitar from a lot of noise.

There's only so much you can do to reduce the noise on a hollow body as you can't shield the inside of the body, so you are mainly reliant on the efficiency of the humbuckers to reject noise. If the humbuckers have been built with a mismatched number of coil windings (to make them sound more 'open'), then they won't reject as much noise as humbuckers with the same number of windings on both coils.

IIRC, you've used mainly shielded cable for the long cable runs, so there's really not a lot more you can do.

And even shieled solid-bodied guitars with humbuckers can still hum a bit if there's a lot of electrical noise about. But the grounded strings are doing their job and the noise is being reduced significantly. You just need to learn to keep your hands on the strings as much as possible.