I live in the Renmark area (actually pretty well under the approach to RWY25) and conditions here today have been clear and cool with a southerly breeze. The terrain around the airport is pretty flat and varies from vineyards and orchards to areas of open mallee forest. Seeing an aircraft should be fairly straightforward if you are within a km or so.
If a beacon was heard and didn't give an accurate enough position to find the aircraft almost immediately and the aircraft has definitely not arrived at its destination, then it must have been a very short activation, which is ominous (implies fire).