Why don't you try Australasian Jet at Mackay airport. They're all nice enough blokes..they have a small twin and several 206's..busy most days (pretty representative of a small GA outfit) They might let you wash some of the machines for work experience
(Seriously one of the 206's has heaps of oil all over its luggage pod..flies right over my place on left base..I worry about my laundry on the line!!)