Probably the cheapest and best option is to build more wind and not care too much if it increases curtailment.
Yes, all the things mentioned should be looked into and done when it makes financial sense but "wasting wind" is much less a thing to worry about than "burning gas", and I'd rather waste wind than waste money.
Wiki says: https://en.wikipedia.org/wiki/Australia-Asia_Power_Link
projected to begin construction in mid-2023
And: In January 2023, Sun Cable went into administration, the equivalent of Chapter 11 Bankruptcy.