As I understand it, be it UK or AUS Betfair, your IP address will be recognised as from the USA and blocked. However I don't see an issue with you remotely accessing your desktop from the USA, if you can be assured it's connected and running 24/7 while you're away? That way the bets will still be placed from a computer with an AUS IP address.

It's probably still illegal as the intent is still there.