With no F150 in Australia, doing a RHD on just the Expedition would be a bit expensive. The Mustang isn't selling well, so I can't imagine an Expedition would do all that well either. Besides, we want to see the Raptor go well don't we? However, I wonder how well a Loncoln Navigator would compete against a Range Rover in Oz. Or pehaps we'll see a LWD Raptor out of Geelong.
If you think an Expedition is big, you should see an Excursion. I mean holy shit, I sat my 1987 VW Syncro Camper next to one and it was 1.5 times as long, almost as high (and a VW Syncro Camper isn't exactly short), and about 1.5 times as wide.
Maybe the best way to have one in Oz would be to buy the RHD running gear from the factory or from a totalled unit at the wreckers, and bolt it all into an Excursion yourself.
You'd have a hard time finding a shed to park one in though, and you aren't going to fit under the local K-mart carpark I can tell you!