Hi @terraperma . I know Pemberton :) theres a whole lot of Karri down there planted by my Grandfather :)
To answer your question, Tiger worms will do just fine there. In fact, they are more at home there than here.
I used to buy tigers and reds at garden centres there.
In Australia the worm cultures sold are often a mix of Reds and Tigers (Eisenia andrei and Eisenia foetida) and they like the cooler temperatures.
I think the Tiger toilet sounded more catchy for the inventors and marketers.
Actually so far in my reading the worm that digests human excreta best seems to be the malay blue (Perionyx excavatus).
You can have mixed cultures and their numbers will change with the seasons and depending on conditions.
Perionyx are subtropical worms and thrive im the summer.
Theres also African night crawlers (Eudrilus eugeniae) for Tropical temperatures.
Ill take a mixed bag.
You can buy all these in Australia via mail order / domestic online shopping
Youll need at least 1 kg of worms to kickstart your system as they eat 0.6-1 x their bodyweight a day and you need enough to be on top of the amount that inflows.
Im going to put up a post on how we do Ghetto vermicomposting without the need for expensive "worm farms" (towers of death, haha)
That way you can build up numbers over time and save money.

Please stay tuned and ill give thought to alternative substrates and insulated concrete for more variable climates