I think 3 conferences of 6 could work.
Each team plays each other team once = 17
Each team plays the other 5 teams in their conference for second time = 5
Rotation year on year of home ground.
Total = 22
Top 8 based on ladder finish not conference finish.
Conferences:
1. Blockbuster (+ promote game in Sydney):
Collingwood, Carlton, Essendon, Richmond, Western Sydney, Sydney
(5 interstate trips per year - one to each state and 2 to Sydney)
2. Derbies/Showdowns/Sunburns:
WC, Freo, Adelaide, Port, Brisbane, Gold Coast
(10 interstate trips per year - they get that now anyway)
3. Foundation teams:
Hawthorn, St.Kilda, Geelong, WB, Melbourne, North
(4 interstate trips per year - one to each state)