That has merit for me, a small clan of goblins moving across the land hunting for a place of their own, like a chaotic evil Water Ship Down. This gives a good chance to fix that campaign and implement an interesting systems around the sandbox environment.
What is suggest is a simple story of a goblin horde carving out a spot in the wilds after they have been displaced. The players form one of perhaps three goblin raiding parties that are providing for the clan. Missions should work to benefit the horde, hurt the horde if not completed or have a neutral effect that remains internal to the raiding party. All quests should have a shelf life so if not completed they either spring their negative effect change the story or somehow they change. Change would either become unavailable or perhaps changing in nature.
The mechanism for the horde should not be the building one found in Kingmaker, but rather something like threat range. I would not use this to change the clans power but rather trigger events, Allowing the group to deal with larger challenges as their clan power raises. Rewards could often be and increase to followers, a special character or resource or even specialized troops becoming accessible.
Story: The displaced clan feel from attackers across human farm land. Moving buy night their progress is slow but they have been able to avoid conflict. Days on the run have left the group of fourteen goblins hungry and week. Horde leader Guirrzek tasks the raiding party to steal food form a near buy farm.
Stealth Success: The clan move on faster than before and make it our of human lands without challenge
Murder Success: The raiders gain 2 daggers of human quality and present Guirrzek with 10sp gaining favor. Clan is attacked by human hunting party before making their way to the freedom of the wilds
Failure or no result in 12 hours: Clan lose a non combat member moves on slowly. Players are again tasked with a raid.
Story: The clan come upon a wounded hobgoblin and raiders are sent out for supplies.
Success: Clan gains Abul ben Korr as loyal guard for Guirrzek and headsman.
Failure: ben Korr dies and Guirrzek is vulnerable to future attacks.