it will be illegal.
unless there are 4wd tracks through there, and your bike has recreational rego which means you'd also need a brake light and a rec number plate, then it would be illegal.
if there aren't any tracks in the bush then it would just be straight up illegal, no permit is going to save you.
2 of my mates were riding down a footpath on fullsize bikes, a cop jumped out of the bush and coat-hangered one of them off his bike who consequently knocked the other guy off his bike.
they pleaded with him because he was threatening to take their licenses' and they both needed it for work, so he let them go but he said if he ever see's them riding again he's going to come down hard..
moral of the story - its not worth it.
puttin on all that shit to get my bike recreational rego is no drama as I have all that crap. we live out in the scrub and the bush is a long way away from houses and we always hear peoples riding their bikes in the bush. Also, the cops around here are actually alright too! I've been caught riding me push bike without a helmet a million times and they just ask me why dont i have it on and let me go. I supposse I can always ride in the paddocks out here after the farmers have harvested their crops.