Personally, I dont like the AFL monopoly of Essendon v Collingwood on Anzac Day.
Port v Norwood will always pull a crowd so from an attendance perspective SANFL crowds for a season would be boosted even by having a West vs South game on Anzac Day.
I think Port or whoever should pick another public holiday and build up a unique tradition. Queen's birthday springs to mind but only because Anzac Day has a game, Adelaide Cup has a horse race and Easter Monday has Oakbank. Queens Birthday is also Volunteer day so the day could be used to celebrate all SANFL volunteers and other community volunteers (eg CFS, SES, and charity supporters) by giving them special entry privileges (eg free or half price) and some special recognition at half time or in the pre-game build up. You could have 10-15000 Port/Norwood supporters and the same again in volunteers and their families. Total attendance could hit 25,000 without much trouble at all and lets face it, who does anything on the Queen's birthday/Volunteers day public holiday?