A combination of aircraft is "The Best Practical Fire Bomber" Some large converted ex-airliners B747/A380 (not too long to relocate from say Adelaide, Sydney and Perth) could work on large fronts and CL-415 (based at more locations about Australia) could be more dedicated areas, a few smaller and choppers to deal with spots and protecting local areas like houses.
One size wont fit all, we need a fleet with a National approach .