My favorite sauce is Annies for some of the same reasons mentioned below. The high acid content makes the chicken or turkey skin soft and crunchy instead of tough.I know you asked for a sauce but I use the following dry rub instead of sauce on fatty cuts of meat cause it makes it's own saucy bark on the outside:
1T (Tablespoon) paprika, 1T chili powder, 1 T Cumin, 1T onion powder, 1t (teaspoon) garlic powder, 1t white pepper 2 t sugar of any kind. I know buying those all separate is costly but it doesn't have all that salt and sugar in it and you might be able to get all those separate in Australia easier? I salt the meat first either by brining or by just salting and let it seep in for a day, then dry rub and cook slow.