Thanks for the suggestion Kim.
Following your suggestion I looked up this campground to suss out its suitability - you never know in case you've missed something!
Alas, this site is not great for astro. It's in a valley that is prone to fog accumulation. Trees are too tall with no significant clearings offering a good amount of clear sky - the apparent clearings are hanging swamps, which are not like a grassy park, but more like overgrown with low woody shrubs and impossible to hold an asto session in.
When looking for a site that is optimal for astro, there's a set of parameters to look for:
* Set up on a ridge - fog settles in valleys, leaving ridges above the fog
* You want rocky or sandy ground, not grassy. Grass expels a lot of moisture during the night, and forms a lot of dew - this complicates things for your gear and the measures needed to keep it off optics.
* The higher you are, the less the influence of light pollution from Sydney.
* Not surrounded by agricultural land as this has the same affects as turf with dew.
Katoomba Airfield offered all of these. The huge runway area gave us an enormously low tree line. It is on top of sandstone plateau, where fog rolled off into the valley below. The runways are sandy gravel, so dew was never a problem - once we got frost, but as soon as the breeze picked up, the frost evaporated! And being at 1000m above sea level, the influence of Sydney's glow is surprisingly reduced dew to the reduced atmospheric density.
If you think about where professional observatories are set up, they all share the same geographic parameters that we are looking for! Elevated site and rocky substrate, and yes, away from light pollution.
It is not always possible to get these ducks to line up. We can only try to find sites that are as optimal as possible. And sometimes we need to take what we get and compromise. The whole exercise in finding another site away from the Airfield is just that, to find another site that is as optimal for astro as much as we can.
I am actually very grateful for your post, Kim

. Many people who have been reading this thread may not have been aware of why we are being so particular with our site selection. Some people would have thought that a golf course or grassy park would have been just fine, not aware that setting up on a golf course makes for an impossible dew situation that could actually be just about eliminated by looking for a site that isn't grass covered. But, if a grass covered area is all that's available, then that's what needs to be dealt with - compromise.
Alex.