I'm working on a custom campaign for The One Ring, a mostly-sandbox game in which the players have freedom to explore a chunk of Middle-earth. I'm a hardcore Tolkien fan so I have no trouble with the lore, but the RPG does not (yet) have any rules for establishing a base of operations for the players. Specifically, in my game the players will be the first generation of rangers after the fall of the north kingdom and will be establishing the rangers' presence in the wildnerness.

Are there any generic or system-agnostic base-building mechanics? Things I'm interested in having is an establishment of an economy (the players can set up trade with other factions, mine, chop lumber, and so on) that gives the players a certain amount of resources every "development" phase, NPCs that perform specialized roles in the base and can give the PCs advantages in their adventures (a dedicated healer, a spy, a blacksmith, etc.), and a defense/combat mechanic for if (when) they get attacked by raiding orcs.

I know there are dozens of base-building systems out there, but I don't want to have to graft something onto the One Ring RPG that feels completely out of place with how the rest of the game works. My hope is to find a system-agnostic baseline and goose it to fit in with the One Ring style and mechanics. Anyone know if such a thing exists? Thanks!