Well here's my two penny worth !
Mentioned earlier.........................Airhawk & ear plugs (these are the ones that work for me....Howard Leight Fusion Reusable Ear Plugs)
Soft luggage if it's going to be rough. Hand guards and a screen to lower fatigue.
With an Enfield you can throw away most things that break and replace them when you get home
Spare cables & basic tools to remove wheels and fix punctures.
And as an aside. I really don't think you need a "big" bike for long distance but of course Aus might be different. A big bike is needed for speed and the speed you need to travel is decided by your own mindset. Most of my distance stuff here in Europe is on a C90 or a CG125.............bet i see more than the GSers