First, make your hay storage universal, you never know which kind of bales you may use next.
Second, you will have to move hay around anyway, so think about unloading and stacking a whole load at once to store it, then how you will be feeding it.
Most that buy hay in volume, if hand feeding, have a hay shed/barn and take so many bales to a spot inside the horse barn itself to feed flakes from.
We have a quonset barn where the hay is stored.
We can put about 2000+ small bales on one 80’ long side, 4 bales end to end back to front, easily.
We built our small barn attached to the quonset barn, as a large overhang to it.
We take bales over in a dolly and feed off them, or put the needed flakes in a manure cart with a rubber feed pan, stacked on it and feed flakes directly off the main stack in the quonset barn with it.
I would say, how you arrange your hay barn will depend on how many times you will have to go there for hay.
How often will you get a dozen bales to store in your horse barn, once a day, a week, a month, in what kind of weather, how hard to access with whatever you use to take hay over, a pickup, a gator?
All that will make a difference in deciding where to store the hay.
Where you are, you probably have a closed barn, so storing large volumes of hay in another barn makes sense, to keep any fire in the hay confined to a different structure.
Here, where so many barns are metal and open, to have one end designated for hay storage is not as much of a concern.