Gungahlin is on the Nth side. So you have EPIC, Carotel, Eaglehawk and Canberra Motor village. EPIC is the closest to gungahlin (dont think there is anything else out that way), its literally 5-10 mins away max, my only concern with that place is that the camp sites seem to be either on the Flemington Rd side which leads out to gungahlin - traffic along there can be pretty constant (no trucks with air brakes though) or on the Hwy side. Carotel wld be next closest, then Eaglehawk which is off the hwy as you come in to Canberra from the nth - always seems to be busy, so may well be good. The place in O'conner wld still be my pick as its near a quiet residential area and is surrounded by reserve - but its probably a 15-20 min drive to Gunghalin. May well be pricey too.