Or as the more egotistical mad scientist might call it ‘Ruby Base’. This is at about 1km scale hex. The island is approximately 2 standard ‘day travel’ wilderness hexes N-S. Volcanic terrain of course making that part somewhat tougher.
The fantasy 1830 version of such, anyway. Lord Howe Island is an extinct shield cone – much smaller than it used to be. Natural place for an evil villain lair.