You'll have to go west of the blue mountains for that - to Hartley at least. And no camping.
You might get night sky and a tree at Hargraves lookout or Mt Blackheath, both on Shipley plateau.
You might get the odd rick and sky anywhere along the cliff walk between Sublime Point at Leura and Katoomba but this is a very dangerous place to be in the dark.
Hassans walls at Lithgow has a bit of the "stone pagoda" formations along the cliff top too it again extremely dangerous in the dark.
Only camp spots are at either Euroka camping ground (in the park south of Glenbrook) or at Blackheath.
It is easier to drive home than mess with camping.