I toured around Aus on an F650 back in 1996. Maybe things have changed, but when I did the trip there was virtually no traffic on the interior highways. I could (and often did) ride for hours without seeing another vehicle on the road - and this is on the paved highways, not back roads or trails.
Unless things have changed drastically since then, I can't see you having any major problems doing it on a small bike; it will just take you a little while longer to cover the same distance.
Bruce Clarke --- 2011 Kawasaki Ninja 250R (black)