Thanks for taking the time to respond in detail and for sharing your valuable experience.
I know what you mean about boats getting hammered and the toll it takes. I brought a 20m fast cat around from Queensland to do this very job 6 years ago. She got hammered on the east coast (remnants of cyclone Guba) and found it very heavy going plugging into the strong southwesterlies on the trip down the west coast and we were forced to lay over for 3 days in Carnarvon.
Upshot was that she wasn't very fast when we got her here and she didn't get the trip, with massive compression going on between the hulls.
Like the sound of the triage nurse
Seriously, in these days of ultra litigation, we would not be able to take any unnecessary risks and would need to establish an operational protocol in conjunction with some sort of triaxial impact measurement. (Thank you America !)
The good news is that the weather is usually pretty predictable between October and April. Overnight easterlies get burnt off late morning to be replaced by the strengthening Doctor in the afternoon, which subsides with the setting sun. The easterlies are not a problem as there is no fetch and the seas do not therefore get going 'til early afternoon and as I pointed out in the initial post, we should be running lightship into these seas.
I hadn't banked on a spare boat
but did anticipate that we would need a spare outboard. Think we'd have to go with 4 x F350s as we would need the deckspace to accommodate all the seating but I'd be happy to learn otherwise.