Yes, the 'wild side' of Kadavu is the best fishing but winter weather can make it tough. Like you say, jigging is excellent at Solo, especially if you can fish the wild side or the Durville Channel. Wahoo packs there in winter, best place this season was the NE corner.
Gau definately looks promising. If you can't make Gau, can you make the Golden Mile on the SE side of Beqa lagoon or Cakau Lekaleka ? Some great fishing there. The Coral Coast game boats usually work the bluewater but get in close for some good GTs and dogtooth on the zero droppers.