I have skimmed all 6 books of this adventure path and read most of book 1 in greater detail (I haven't read through all the exact encounters in the dungeons as I tend to read those last.)
I am at current really confused by the concept of my players wanting to risk life and limb traveling across continents to help this noble chick from their home town become an empress. It very much to me as I read it feels like: PC's do all the work, NPC's get the best reward at the end. Even with the traits to try to force backgrounds to match up with the NPC's it feels like it's going to be very flat.
As a result I'm torn as to if I want to involve Ameiko at all beyond when she falls into the coma in book 1. I'm considering using her death as a trigger that makes the PC's Scions of the distant kingdom when they find the Amatatatsu Seal. Then simply using the other NPC's as support with the caravan.
Though even the other NPC's I'm not as certain about. I really like the elven ranger even if her reason for being there would need to be altered slightly. The elder cleric and the rogue fall flat for me as a storyteller. I'm considering just making some of my own NPC's that have more investment and reason to go along than some of the ones that are premade and should my players want to use the relationship system just building their own boons that could compliment my group as a whole better.
As for the caravan and any possible encounters, at current I'm planning to let my players decide if they want to run it. If they don't then I'll build generally what the caravan has and convert any caravan encounters to just encounter's for the players to deal with as it makes it more of a living world. (I plan to roll all encounter tables ahead of any sessions so I know what will be happening on what travel days. Any variation I can adjust for on the fly but then I'm not sitting for minutes rolling percentage dice while the players are waiting on me.)
I'm curious if anyone else has tried to run this path without Ameiko or the other NPC's and how it went for them if they did.