Good summary and includes some of the rumours which may or may not be true, but if true paint a very good picture of the possible scenarios.
I don't think the CSK necessary worked as a hunter, if you cut the victims throat then its a way of almost certainly ensuring their death. If you strangled the victims first and moved them to their dump locations, slicing their throats is a way of making sure you don't leave a witness. Maybe after Karrakatta the CSK was terrified and the throat slicing comes into play at this point. The victims were all found some time after they were killed so its unlikely in Western Australia's climate that any evidence would have been left on any plant/sand. The area is too harsh and extreme so surely the water run off and also the harsh conditions would have made finding evidence that they were killed at the site almost impossible to determine. If they were found within a few days then it may have been possible to make a determination whether the victims had their throats cut at the dumpsite, but definitely not after the time they were found.
Sarah was dumped in summer too so I wonder if he took more care and placed her alot further away, eg. Rural WA, to hide any evidence and likely hood of a walking passerby finding the body, would make sense if this new discovery turns out to be Sarah Spiers 3 hrs east of Perth. Less chance of rain washing any evidence away and more likely animals would consume the remains.
I think he probably accidently killed Ciara and then just dumped the body and didnt bother going to the interim location, or maybe he did hoping she would regain conciousness, she didnt and because she was not 'alive' could not get any gratification out of the situation and moved on to his ultimate fantasy, taking the girl to the dump site, slicing her throat, and dumping her in a place and covering her so she may not be seen very easily for a substantial amount of time eg. when the evidence was mostly gone.
Point 1 doesnt need much eplaining. Traditionally abductions were typically 'blitz' attacks from Vans pulling up beside a victim and someone running out of the side door, tackling the victim before binding them or disarming them and basically throwing them into the Van. This is actually more than likely similar to how Gerard Ross vanished (A forgotten WA case that never made a Coronial Inquest sadly. Poor kid, not even our government could care to find the killer enough to give him an inquest, and this was before the CSK). However after reading the news articles from the CSK case and the recent articles surrounding Karrakatta and the new theory of 'blitz attack' then it seems likely the CSK method of abduction didnt change much from Karrakatta. Serial killers tend to keep to patterns that work and not change unless they feel they may be discovered. The Karrakatta abduction worked incredibly well and he got exactly what he wanted from the attack by the looks of it so its unlikely he changed this approach too much. That late at night it would have been obvious if someone was lurking around asking people if they needed a ride, straight away the element of surprise is lot and you have made yourself a number of witnesses that could lead to your identity being found. If this Person did this all the time it would be even more obvious. There were reports about the Police Officers son asking people if they needed lifts though, and he could have access tot he Commodore VS Series 1 'White' especially if that was a Police issued vehicle as the cops drove that exact vehicle in those days, so you never know, maybe the offer of a lift never worked, or only landed a male, and then you had to actually drive them home. The blitz atack guaranteed you got the victim you wanted, eg a female of a certain age, and no witnesses if done in a secluded car park behind a business late at night and you surpirsed that victim eg. Karrakatta
Good chance the killer has changed MO and has still raped/killed. Left the state and continued somewhere else, or just stayed under the radar to let the heat cool down, or simply felt he was about to be caught, and by pure luck and lack of any actual physical evidence has incredibly escaped capture, despite the Police thinking they know who it was.. All possible scenarios.