Tinderry Peak is 1619m. Can see Telstra Tower on Black Mountain on a clear day (maybe 50-60km line of sight not sure exactly). Was last there 1980 and found a jar of Minties no doubt left by a previous expedition.
The Brindabella mountains are 200-300m higher than Tinderry; unsure if there are any private observatories there.
The Orroral laser station is at 1349.887m. Does this count?
See
https://cddis.nasa.gov/sgp_sitecat/orro_home.html