I have booked an unpowered camp site at Echuca Holiday Park for the Friday & Sat nights, but will probably just buy a day ticket for the Saturday at the music festival. I did the same this year and had a really good time. You can take your chair and esky with food and set up for a really enjoyable day / night. Festival tickets for the full day/ night on Saturday are $60 and a full weekend pass is $110. The tickets were available this year right up until January, but no guarantee it will be the same for next year ( day tickets are limited and sell quicker also) it's up to you as to how long you hold off before buying your festival ticket, but if you want to camp at Echuca Holiday Park you should do it sooner rather than later. It's a lovely big park with a swimming pool but they only have 3 unpowered sites and I have booked one of them ! if you want to come along tell them when you book that you want to book unpowered site 2 or 3 if they are still available, otherwise the powered sites 90 - 94 are right next to the unpowered sites so we can all be together.
Here's the links :
Echuca Holiday Park http://echucacaravanpark.com.au
Riverboat Festival. http://riverboatsmusic.com.au/about/