The SM is good but I too lean towards the Super Duke, it is a very good overall package. Lack of touring bags are an issue in your case, but a little Aussie ingenuity should resolve that. The SDR has much sharper edges than the SD, a couple 240k legs with a stretch shouldn't be bad. The SDR motor probably has limited range compared to the SD but not too much when cruising. A camp fuel bottle or two would make it equal on trips.
I just took mine out through the favorite twisites today and it's a sharp handling, firm suspended beauty. But she urges you to ride her and explore limits, and induldge in the howl of the 52mm throttle bodies. Relaxing? Depends on the person. Enjoyable? Absolutely!
I'd love to do a lap of Oz, I have a good friend who lives in Shepperton and has a holiday house over looking the Great Barrier Reef, that would be my trip of a lifetime. Austalian GP, Phillip Island MotoGP or WSBK, Touring car race, play the Sandbelt golf course, get pissed with the locals and ride the lap...............game set match. I might even take in a cricket match.