“……. for rider comfort and to ward off frostbite as there will also be some 20 odd creeks and rivers to cross. 
wet boots in snow is a no-no!”
If you plan on riding during august, you have got buckley’s chance of getting across 20 odd creeks and rivers on bikes, let alone a 4wd.
Best time to ride is November to May.
Some of those creeks/rivers are raging torrents during August with the rain and snow melt.
Good luck