Well, there are always two kinds of mods ->
The ones that make it more balanced
and the ones that make it overpowered (some part of the game goes overpowered - what I as megalomaniac totally understand)
I could imagine that very good core code master could make one of the backup slots to normal slot (or even both) - would that be overpowered? Well - it is mod - it is on everyone if he/she choses to use it.
Even in the normal game I sometimes chose to have only 4 or even only 3 slots populated (hoping to get more XP), Also I believe that I have enough work already (mental/planning, physical/clicking) with 5 armies
