Miniball? What the?
Just add a toymaker than can make customzied copies of any miniature that is already in your HoM, and that can also dedicate them so they get added the next time you enter the HoM (Like Kimmes adds things to your HoM without you being in the HoM first).
Then add a miniature slot in the inventory.
Talk with the toymaker, pay 10g, he makes you the copy of the miniature, and you put it in the miniature slot.
The miniature slot would have the little icon to hide it automatically, but it won't have the "show in outposts" and "always", to prevent people automatically taking use of the 20 slots in outposts, so it would just have the "hide" so it doesn't show automatically and "show automatically in combat areas" so it gets show automatically there.
And done, the miniature will be shown automatically in combat areas, and although you will still have to doubleclick on it in outposts it will be ready to use as soon as you zone in without visiting the storage.
As for the summoning stones, they are consumables.
They taking up slots it's one of the downsides for using them. You might not like it, but that's the thing with downsides, you are not supposed to like them.