Unless Australians are comfortable with sending a much larger number of lower house members, that would make the electorates get much bigger than they currently are

Your idea would result in a 225 seat house. Mine would be 250. Not a significant difference IMO.

I actually most of all would like to see a move to MMP, the system used (with some minor differences) in NZ and Germany. Where you elect 1 per division locally, and also vote for a party, with the party vote being roughly 50% of the total seats in Parliament, and used to make the total Parliament proportional to the will of the people. The biggest differences I would like compared to the Kiwi & German system is to let you give a second preference for the party vote, used only if your first choice doesn’t reach the 5% minimum threshold to get any seats, and to choose MPs in the proportional system based on nearest loser, rather than by a party-provided list, so if a party deserves 1 extra seat based on its party vote, the candidate from that party that gets the seat is the one that got 49% of the seat vote, rather than being the person who was pre-selected by the party to get the highest priority.