12 teams would be great. A 22 round competition plus finals would be such an improvement on what we had now. With the teams and states you suggested, they could even run a conferenced system if such a long season was unaffordable (i.e. Southern being TAS/VIC/SA/WA and Northern being ACT/NSW/QLD/NT).
I’d like some of the midweek games to stay as well, even with the 8 team comp. If they structured it as one midweek game and four on the weekends, teams in the existing comp would only need to play midweek every 4 weeks. Saturday/Wednesday/Sunday is enough time to recover I think, especially for teams where not so much travel is involved. It also means we can consider taking matches away from Saturdays when a lot of fans are out playing and cannot watch.