talk to australian 4wd insurance
seriously i was with nrma & luckily never had to test them, however when i got my defender with a uk scorpion extreme suspension kit in it, nrma said thanks but no thanks, despite us having the house,contents & discovery with them.
i checked aust 4wd insurance and they cover you everywhere( i mean EVERYWHERE!) & they were so much cheaper than the others & they cover absolutely al the accessories you list.
can't say what a claim is like but i just chipped the windscreen & they offered a free glass replacement every 12 months.