I don't know how the ZoC on Outposts really work but here are some ideas/observations I made.
1. When hovering over the Outpost-Button I would like to see a preview how the ZoC changes if the Outpost was built on the very spot
2. When an Outpost gets razed I would like the camera to get moved to the place and not just get a "outpost in the north razed"-message.
3. Sometimes an outpost gets swallowed by another ones ZoC. I think in that case an undefended Outpost should turn sides or get razed. (that would help with this "problem": in FE you can move through other territory - so you are able to place Outposts "behind" other players. The only option to go againist that is by declaring war and razing these outposts. With ouposts getting razed by the ZoC you could avoid declaring war).
4. Did you consider Outposts getting better with traits or technology (garrisson, fortify-level)?