G'day munch, it's an awesome place and a great time of year for a trip out there.
I agree with Cam, there's plenty of nice spots off the beaten track if you just follow your nose. Maybe find some features you want to check out on your map and aim to camp nearby or maybe camp somewhere with easy access to a view for sunrise and sunset - which can be pretty spectacular over all those domes.
I think there's 7 official bush campsites (I can send you the grid refs if you want) but after seeing them all and staying at a couple I would only really recommend the Sth Bald Rock and Underground Creek sites. The others are mainly small cleared areas in the bush or on the side of the track and not particularly interesting. Just don't leave it too late in the day as I've done a couple of times and find yourself setting up camp in the dark in dense scrub
The south bald rock site is really nice. You camp by dingo swamp at the base of some big slabs which are great for exploring, and provide nice easy access for an elevated sunrise/sunset. There is also a small creek nearby which is handy as water can be an issue out there. Underground Creek is a fun place to explore too and it's nice and close to the Aztec Temple or the ridge walk down to Twin Peaks.
The twin peaks spot is cool but the last two times I've been there I found rubbish strewn around, used toilet paper and an ugly scar from someone's camp fire blazed onto the rock. It made it pretty unappealing and I continued on to somewhere else. That kind of thing makes me wish that it was still a secret as it seems to be attracting the wrong kind of people...
But seriously there are a lot of excellent places to set up a tent and I'd recommend maybe having a look at mallee ridge or wallangara ridge too, and wake up to an epic sunrise down the valley of the winds

ALWAYS be yourself.
Unless you can be outside, then ALWAYS be outside.