I like the base idea of Second Darkness, but it is widely considered to have problems - tone shift from scum and villainy to saving the world (combined with generating the false impression the campaign is centred in Riddleport) and the elves are...unsympathetic. The latter is not that hard to fix by just playing them differently, but the first is a bit more trouble.
I've seen the suggestion of using Souls for Smuggler's Shiv as a first chapter, and thought this might help, though obviously a few changes are needed.
1) I skimmed Souls and didn't find much that NEEDS to be tropical, so it can be reskinned to a temperate forest island, perhaps once part of Alaznist's empire (which is mostly underwater I understand). Alaznist was a demon worshipper so a temple of Zura isn't a stretch, and the cannibals can be like the Picts in Conan.
2) I'd like to replace a couple of the castaways with Kwava and Samaritha (she's already the apprentice to a cyphermage and is on the way back from a fedex mission for the boss), levelled down to L2 for convenience. I only have 2 players so the source of NPC assistants is useful in any case.
The faction connections in Souls are:
Red Mantis
Pathfinder Society
Government
Aspis Consortium
Pirates of the Shackles
The pathfinder society and Aspis consortium are fine as is, the rest leave something to be desired. My recollection is that Kwava's part of a mercenary company that sometimes works for the Winter Council. With Samaritha, we'd have cyphermages as a faction. The pirates could perhaps be replaced by one of the gang bosses in Riddleport - Zincher's gang (this could make the pirate lady's chapter 2 quest killing Zincher or otherwise getting her free of him)
3) Obviously replace the serpent traitor with Depora Azinrae - part of the ruins on the island is similar to the cyphergate and she decided to study it to see if it gave further insight. To get Depora to CR 6, I was going to add a level and make her noble (also gives her suggestion 1/day, explaining how she controlled the captain). I might need to give her spellcasting levels (perhaps shift to L3 fighter L3 cleric (abraxus)) to explain how she got past the lacedons - she'll have enough feats that rebuke undead won't be a hardship.
Children of the Void - connect the PCs to this by quests from their fellow castaways. Samaritha and the Pirate lady are already on the island with their own factions - Kwava's mercs and either the Aspis or Pathfinders could bankroll the PCs expedition with scholarly/heroic as well as monetary reasons, and while there they can rescue Samaritha from Akatas and pirate lady from Zincher.
The shift from medium track to fast track is an issue here - I could either retcon the xp and just switch to fast track, or add extra xp in the form of side quests and random encounters - getting into a fight with Zincher's crew after arriving in Riddleport would be good forshadowing of eventually fighting him on the Island.
My main hesitation is that I would half like to run serpent's skull as well (for all that it is about as highly regarded as Second Darkness), though there the big change would be I'd use one of the more common firearms rules for a more Solomon Kane feel, and don't know that I want to reuse Souls.
