You'll need to stop for a receipt (does not need to be for fuel) at least every 600 kms. I got caught out once when a servo was not open. I was able to get to the next servo about 100 kms further on but the IBA ride was blown.
On another IBA attempt my fuel receipts flew out of a side pocket. I now photograph each receipt as I get it.
Check each receipt's date/time for accuracy. Some servo's don't adjust for daylight saving. It's probably not such a big deal on a SS1600.
On one of my more strenuous IBA rides, Port Augusta to Darwin, 2723 kms in 24 hours, I arrived at my planned servo in Darwin with 15 minutes to spare and feeling very pleased with myself, until I noticed a problem with the receipt. I quickly found another servo just in time which saved the day.
I live in Canberra. How long are you planning on staying in Canberra?