I reckon Jetstar would be good out of LEA (Exmouth) maybe a PER-LEA-SYD route a few times a week in the peak season (april-october) A lot of backpackers go through there and potentially a lot of demand if flights didn't all go through Perth and are expensive, but there definitely would be demand I would think given how many flights there are up to North Queensland. They have tried LEA-MEL using QF but it would be mostly leasure traffic, so that never really made sense to me. QF operates PER to LEA a few times daily, they might not want to cannibalise profits on that route. Another option could be LEA-BME-SYD possibly.