How does this idea sound?

Arrive in Christchurch March 1st, travel around New Zealand for a month or so. Reticket to pass through Sydney with a month or two layover on the way back to the states. Visit the coast of Austrailia a little bit, but then catch a flight to Beijing or Hong Kong. From there, take the Trans-Mongolian branch of the Trans-Siberian Railroad to Ulaan Baantor. Travel around Mongolia a bit, return to Sydney by rail and airplane as before, catch plane to states, head back east, then back west...