Depends where you're coming from I suppose. You won't be facing any traffic either way at that time of a weekend. If I'm travelling to the Mountains from the City, I usually take the M1/M2/M7 then onto the M4 from there. Yes there are tolls but I get most of it back at the end of the tax year anyway. Going that way, I can get from Pyrmont to the upper mountains in well under 1.5 hours and it's an easy drive, no stop/start and speed cameras like you get on Parramatta Road.
Well, from my place (East Hills) the biggest pain of driving to the mountains is just getting to the western freeway. And no I won't use toll roads except for the M5.
If I did want to drive a looong way for complete darkness and isolation, I'd maybe pick one of the clear-felled forestry areas out at Newnes, or off the road to Jenolan.
Btw, it's not on a weekend. It's a Wednesday night.
Stanwell Tops would be nice, but it's a very popular spot. That car park at Bald Hill isn't huge. Maybe Geoff (gnif) will let you borrow his backyard, he lives up in the mountains ;-)
Bald Hill isn't a very popular spot around midnight on a Wednesday, except for other eclipse-watchers. Also the car park has recently been greatly expanded.
There are some good spots along the escarpment edge too, but I'll have to check night-time accessibility.
I know of multiple remote bush clearings in the mountains with fire trail access, that would probably beat gnif's backyard.
But the drive is too long. Don't forget to factor driving back home after. Unless I go remote enough for camping overnight. Like Newnes. But that would exclude everyone who works the next day.