Spotlighting at any of the NPs surrounding Moogerah will produce oodles of Robust Velvet Geckos, Tyrons Velvet Geckos, the usual snake suspects like Brown tree, Small eyeds and Coastal carpets with the odd Spotted Python thrown in too.
The track at the dam wall closes at sunset. At Mt Greville (the mountain at the southern end of the lake) the track starts on the Eastern side and it's easy to get disorientated in the dark.
The best bet would be to go to Mt French. It has a groovy Western facing cliff which holds heat well, has a track to its base and is just a matter of keeping your eyes open with a good torch. Car park is at the top of the mountain too.
Plenty of non herp wildlife to be seen at night in the area as well.
Good luck, and post the pics up afterwards when you are done.
cheers