Wouldn't it be easier to get a Shuko or UK pigtail and cut the plug off and install an Australian 15A plug, I believe they are both restricted to 13A charging. At least that way its completely safe (dont have to remember to dial down to 15A) until Tesla can release a specific Australian 15A pigtail. It might even be wise for Tesla Australia to make these available to customers as a temporary solution. Any word on if they will actually release an Australian 3ph pigtail so the number of adapters to be carried can be slimmed down.
Could do that, but means yet another pigtail (rather than a second adaptor for an existing pigtail) and at 13A it's debatable if it's worth it over 10A (some would argue even 15A is not worth it, but for me 50% faster charging in some situations is well worth it).