Player wants to build a trade empire, need some advice. potential ROTRL spoilers, beware.

[Movin]

I'm a GM from a group running a ROTRL game. One of my players recently had a character die and brought to me the idea of his next character being the child of a trade tycoon. He wanted to have his character endeavor to create a trade empire and take over the world. I bartered him down to just working on Varisia for now.

What with the premise of ROTRL this gives me some excellent chances to foreshadow certain villains that normally don't get much limelight till much later. Right now the group I'm GMing is just starting on Thistletop so I figure much of this is for later, but good to have it now and not need it.
What I'm considering doing is dropping the experience progression of the group and tossing in some extra side quests and missions across Varisia.
This would give me time for the character and the party in question to gain contacts and amass resources in an organic manner.

I'm not sure if the Kingmaker rules would cover such a thing as trade routes or even begin to press on the idea of rival nations and companies exerting their economic might. I get the feeling, with my read through of the nation rules, that as the system was not designed with such a thing in mind that it would fall flat and be more harm than help in emulating what I want to.
I think this might be possible to make enjoyable but I lack the experience to do so and would prefer to find a balance between difficult and impossible that makes the character cry and the player smile.
So, I ask anyone who has had the patience to read this rambling message.

Have you ever GM'ed for a player or group of players that wanted dominance of the world though trade, what did you find useful and what did you find did not work?

Advice and suggestions of any stripe or flavor would be appreciated, thanks.

[Shizvestus]

Couple of ideas: pick up the Kingmaker set and read through it. Use the ideas in that for kingdom building. Also there is something about keeping up a keep in the ROTRL magazines that details all you need to know to keep your little castle going. You are going to run fort Rannik for a while and you could Kingdom Build right there... Trade between Korvosa, Magnimar, and Riddleport (the Freeport of Pirates and ner'dowells) can make you rich. There is also the Dwarven City and the city of Kaer Maga at the stairs of the Stoval Plateau that are both major players in the area and lots of small towns that belong to one city or the other... Like the lycanthropic town of wolf ear...

Get the next couple of sets of Pathfinder Adventures as well - the Korvosa one and the Riddleport one. Korvosa covers the Varisians and their Scarni thieving bad side as well as rogues and merchants in that city. And the Riddleport one has some great contacts in the rogues and merchants in that city as well.

[Shizvestus]

Right - Curse of the Crimson Throne and Second Darkness Pathfinder Adventure Paths ;)