"the other two centres are Townsville and Cairns with similar flight times."
1. There are also fully equipped SAR helo's at both Rky & Mky
"and trust me, fixed wing will not be the initial response for 50 km off the coast.'
2. Now that will totally depend on many factors and obviously more factors than you wish to include. Really that is a very inexperienced response as 50km off the coast in the total length of coastline can sometimes leave the most immediate response and closest response is fixed wing.
3. Thankfully this will not be your decision