My flatmate and I kept Kowaris and some native mice (not spinifex hoppers) many years ago. We also fostered orphaned fruit bats - nothing like a big fruit bat hanging off your hand to scare off the Jehovah's Witnesses! (That was a VERY funny encounter...)
Anyway, the Kowaris belonged to my flatmate, but were pretty easy to keep. I think she'd gotten excess stock from someone at Taronga (?). We fed them a bit of dog food, some mixed veg, regular treats of meal worms and pinkie mice now and then. They enjoyed bogong moths, too. We kept them in a big aviary and a concerned neighbour once reported to us that we had rats in our parrot cage because she saw them running around at night.
I also spent a summer working in the Research Dept of the National Zoo in Washington DC. They kept a variety of marsupials including some S. Amer. species, sugar gliders and ringtails. The South American Monodelphis are much like the kowaris in diet and size. The zoo diet was minced vegetables (sw potato and kale), meat, fresh crickets, mealworms, a bit of fruit and pinkie mice as treats. That summer got me hooked on marsupials and led to the move to Australia - never know where your interests will take you!