I understand that you don’t want to take the mount and blade path of becoming a lord, because then people could just play warband. Would you instead consider a base camp that can be relocated. For example, when clearing a abandoned fort, you make it into a base to stash goods and train recruits, but process of fortifying it could be pricey and require resources other then gold to balance out the benefits. Then if the player decides they want to move basecamp to a different abandoned castle or fort you would just have to clear it out while having the proper resources in your inventory (Wood, Gold, Cloth etc.) Penalties like having your base attacked for staying in one place for too long can be added where the player has a day or two to rush back to “lift the siege” or else lose their trophies and garrison and leaving their base like a burnt out village attachment. This could satisfy players urge to have a storage/trophy and training base without granting them a theme breaking fief and lordship. As for training this would only perhaps give farmers and fishermen a single level or maybe not a level but stat boosts that you could pick like training them in marksmanship. As I mentioned before this should only be achievable by a well established mercenary group that could afford the expenses for the benefits these thing would provide, after all the Jomsvikings had a base, so it is not so strange to think mercenaries would establish temporary bases that would move depending on what noble house they were serving.