The common denominator here is all of these girls left the club to make there way home/friends home and most likely all 3 wanted a taxi, I highly doubt any of these girls would grab a ride with a stranger let alone all 3 so I think your scenario is extremely plausible. being blitz attacked while waiting and bungled into the boot seems less likely than actually entering the taxi and being blitz attacked as it is the most logical scenario and one that fits what little evidence we have.
1 Two girls waited for a taxi and the third more than likely needed one.
2 A taxi gains instant credibility and trust.
3 Some taxi's were the make and model of fibers found on CG.
4 A taxi was spotted early hours of the morning near a dump sight in an area not well known for taxi's
5 A taxi driver was known to be in the area at least on one of the nights a girl went missing whom was a prime suspect of Noel Coward
These girls entering a taxi would not seem at all out of the ordinary, if Ciara was blitz attacked surely the 3 guys that called out to her would have heard something, not to mention any other potential witnesses. I think it is very logical to assume the incident you referred to was linked. It might well not be, but to rule it out completely would be stupid.
http://www.mako.org.au/steven_ainsworth.html Steven Ainsworth, the guy I mentioned a few pages back with a similar MO of bashing/raping women in the ally beside or near pubs/hotels was a driver, I'd be curious to know if he was a taxi driver or something similar or if it just means he was a truck driver e.t.c as the article didn't clarify.