Phil,
Any National Park like either Bobbin Head or the Royal National Park do not like large groups like car clubs etc. attending for their BBQ's etc. The Camaro Firebird Club who have held there Annual BBQ and Auction there for I think 15 years or so, were just hauled over the coals by the National Parks and Wildlife Service for such an event a couple of months ago.
As for the 100 or so cars over the Harbour Bridge, permission from the NSW RMS is required and also the NSW Police Force. Ford Australia attempted to do this with the Mustang 50 year birthday celebrations and found it too difficult to put together.
As for putting another run together, Hak and I are constantly chatting and throwing ideas at each other, and something will come to fruition.
Or maybe Phil, you should organise a run as you have all these ideas. You can organise the event,,you can deal with all the agencies to reserve the venue, you can promote the event, you can go and do all the purchasing of all the food, you can print all the maps, you can lug all the food etc. to the venue, and you can even cook the BBQ too, and last but not least, you can do all the cleaning up as well.
Actions speak louder than words!