If you could find a sponsor in rural Australia, as "Aircraft Pilot" has an ASCO Code of 254111 could could probably qualify for a 457 Visa.
Whether you could find a sponsor with only 300 hours total time, would be highly unlikely, especially as your sponsor/employer must pay you the Immigration Minimum Salary Level of $41,850, plus other costs peculiar to the 457 Visa program.
I suggest you take the Flight Instructor route as possibly your only practical way to remain flying in Australia.