Yeah, there are a lot of cool perks that can be given out based on location.
Several of the incoming City Enchantment Spells focus on this idea of fighting within your ZOC (close to cities and outposts), where bonuses are given to your forces and penalties are given to your foes when you're fighting in your borders. There are also spells that given bonuses based in the terrain type being fought on.
Between those spells, champion abilities, and enchanted items giving similar boosts based on location, I think you'll find your suggestion works very well in practice 