Forget Fiji. Keep it simple. Sharks should be look at a public holiday game or 2 at the new SFS. Every other club takes 1-2 games away, and most have a public holiday game that gives them an almost guaranteed 30k gate every year.
Sharks v Panthers, 1967 Cup or Preston Campbell Cup (or something)
Game 1 at the SFS on Easter Monday
Game 2 at Parramatta on Queens Birthday
Tbh the matchup doesn't really matter - it could be St George, Manly, Roosters.. irrelevant. The key is to get into a big stadium and get it on a public holiday.
The 3 clubs that are sticking to suburban grounds (mainly due to distance) need to make sure they can still get some big gates above 20k, or in the new stadium era they'll be dooming themselves to irrelevancy and thus relocation or death.