I do not know where this sits with RA-AUS but being in Maintenance at one time, and on other occasions wanting to get away at first light I have often operated GA aircraft late at night without a night VFR rating, ground handling/taxing and re-fueling only.
I have even on more the one occasion started up about 15 minutes prior to first light, done my checks, warmed up the engine and sat at the holding point for a few minutes while I waited for the correct time/sunlight to appear over the horizon before take off. (As a side note I have some time night flying on my USA licence to back up my experience operating on the ground at night(no night rating in the USA, just part of the PPL))
The main factors I see with this is do you have the ability to NOT push it by taking off prior to first light!!!!! And as for landing that close to last light, no if you land that late, just go to bed and think about how crappy your flight planning was!!! Also if you do run into something, be prepared to cop the bill as I doubt you insurance would cover you!!
The big problem I have with the way Mick is asking his question at start of the thread (Not shooting you down at all Mick, have no issue with what your saying) is it sounds like a way of creating a convenient excuse for pushing the limits!!! Especially the technically legal night VFR. It's like a technical virgin, it's a lie!!!! Also Mick I am fairly confident (as in 99%) that unless the regs have changed, GA aircraft require a radio navigation aid to be rated night VFR. So unless you pack a NDB or VOR in your RA aircraft, it's not even close to legal!