I live in Mooroopna.
You don't need to join the club apparently. However they have banned Chinese and any clone / knock off bikes. Unless you've got what they consider a " real " dirt bike.. eg. KTM, Suzuki, Yamaha, Honda. Don't bother.
Theres plenty of bush spots. Theres a few great spots just outside of shepp / mooroopna. PM if you need to know more.