If you are really keen to rent before you get here it isn't impossible and there are many posters on here who have done this successfully. But heed others warnings and be careful. You could do things like ask for a skype tour of the property so you can 'see' it as it is. However, with competition for good rentals pretty high an estate agent might not be bothered to do this, especially in the price range you are looking for.
Another suggestion is to look in new developments. New properties are often bought to rent and these will obviously be in as new condition and you will get what you see.
I know from your other posts that you have chosen Port Noarlunga as it is a beach location, looks nice and properties appear a bit cheaper than Brighton which is an area you were initially looking at. Just be careful of other costs that may be associated, such as longer childcare hours if your commute is longer, petrol and car wear and tear. These could add up to more expensive than paying slightly higher rent in a more central location. I say this as you have no idea where you will be working. Your wife is a diabetic nurse and I know there are diabetic services at RAH (city) and QEH (west) and a high prevalence of diabetes in Aboriginal communities which are often more Northern areas. I can't find much at all in the Southern regions for this specialty. You could consider western beach suburbs like Semaphore or West Lakes / Tennyson. Have you looked at anywhere other than south?