Usually AA membership goes with the driver, not the vehicle , so if you have it it covers your bikes and cars.
My AA has different membership costs depending on the recovery distance, some might have a extra premium for bikes. So check.
I have the max cover which gets me back from interstate, an extra $50- is not a much compared with the potential cost.
No mention of any difference in cover for sealed or unsealed roads, but somehow cant see them giving much cover along the Gunbarrel or whatever, so if real outback is contemplated might be best to check. And get a Sat phone!