I've read Kingmaker and actually, it seems like it would be better for a PBP than a face-to-face game (at least, with the resource management aspects). I do not have time to run it, unfortunately.
The problem I see with it in PbP is that decision making takes a long, long, long time to happen in this format. For an overly open setting/sandbox like kingmaker, it could take a week to decide which hex to explore. Then after a few months of that, people have already forgotten what happened in the first few ones, or what they were looking for. I've found in PbP, that there needs to be a bit of a railroad, too much sandboxiness can lead to paralysis. Too much railroad is no fun either, but although this is one of the coolest adventures I've seen, having like 26 or so hexes to get through plus all the bases/dungeons, or whatever you want to call them to explore it just may be too difficult to run.
Good point. A streamlined system for exploration determination would be wise.
Maybe a PC or NPC leader who could take counsel, but ultimately made the decision. Then everyone could weigh in with a single post, but the decision of the leader would stand.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.