For that reason +1 to the idea, it rewards guys who spend more time in Strat at the expense of cRPG. I guess it is contrary to the intended rationale, but ... well, the idea is good.
But, why should you get advantage in cRPG by playing strat? That is just plain stupid if you ask me. It should really be the other way around, if something (moar time in cRPG, more strat goodness)...this way the people who care about strat are not losing anything, but also the people who dont are not being disadvantaged.
It is all about time management, the people play strat cause they want to, if they do it on expense of crpg time, it is their choice. And tbh i think except few very very dedicated people the guys manage strat while at work or while they cannot play regular crpg, not instead. (Also dont forget quite some time you can spend as dead guy on battle
)
Why not to make an inactive army lose troops over time, not for upkeep, but for boredom? You know, the soldiers want to fight, and when there is nothing happening, they get bored and go work as fletchers or something
There could be timer like few days, and if you did not had any battle within the faction in that time, you would have a chance to lose some percentage of troops every 8 hours or so. This would force people making battles somewhat, also would prevent hoarding large armies for long time.