@MathieuLaroche01 hi, i've done this trip last December with my family. This was our itinerary
Day 1 - Sydney to Canberra : Started driving at 8AM and arrived at Canberra almost mid-day. Stayed and camped at Cotter reserve campsite. The rate is 15$/day with hot shower and toilet but no network though. We spent the day exploring the city and given the size of Canberra, I think you can go to all the interesting places in less than a day.
Day 2 - Canberra to BIG4 Wangaratta North Cedars Holiday Park (rate is 50$/day. Stops along the way were Gundagai and Albury (were we had lunch). Wangaratta is a sleepy suburb near NSW/Victoria boarder. We didn't bothered exploring the town because my kids already enjoyed the caravan park's amenities (pool, game room and playground). It was close to a 6-hr trip (including the stops), so my wife and I just spent the afternoon relaxing.
Day 3 - Wangaratta to Melbourne. Spent the Christmas there at a friend's house and stayed in Melby for 4 days (we even drove to see the 12 apostles).
On the way back..
Day 1 - Melbourne to Gundagai Cabins & Tourist Park (34$ /day). it was close to a 6-hr drive with only 1 stop at Albury for lunch. The caravan park has basic amenities but there is a community swimming pool beside it with a stunning view of the mountains. So my kids went for a swim and they loved it. We also drove around to see the interesting places around the town.
Day 2 - Gundagai to Sydney
On the average, I spent atleast 50$/day for fuel. This is not the best itinerary but it suited us and we enjoyed our trip.