Sorry for the double post, but I just thought of another idea, linked to an idea from that other thread that ties in with yours. It id my belief that one of the major thing strat suffers from is no real system of power. You highlighted the ranks issue, but i want to take it a bit further.
Basically the issue is how to sustain large armies, but give smaller armies advantages/more viability/power I.E the individuals in clans.
Another balancing object I thought of related to troop pay. Currently the system is that once a leader runs out of gold, the troops bleed away at a rate of knots. But this seems inaccurate to me. In large combined armies, individual pay not making it to the troops was a common thing, they wouldn't run away the immediate moment the army runs out of gold. A lot of this was for a variety of reasons. For instance, in Edward I campaigns, he had to rely on his lords providing troops for a fixed term. If the King went to war and it was approved by the Magnates, the individual Earl's of the realm were legally obligated to provide troops for a certain period of time, it was largely up to the Earl's to fund their pay and equipment and it was up to the King to fund the supplies whilst on campaign. In turn the individuals who made up the bulk of the army were required a fixed term service by the Earl's as well, for which they would be paid (but it was well known for this pay to be very back dated, you've gotta love the English ability to keep records). Once that time was over, the Earl's had the right to leave and take their troops with them and the King could do bugger all about it.
So the idea is this. Add a function that allows for the highest ranks (rank 4 in this case but this could need a new higher rank 5) to 'demand' troops for a war in a realm from the lower ranks. If the lower ranks approve of this, then troops are automatically transferred to the person demanding them, along with the gold needed to support their 'upkeep' (troop pay, possibly equipment). Once this has been approved, set a time limit for the main army to hold the troops, for instance 72 hours as a random example. This gives the leader time to make an attack and fight it. This could be automatically defined by code, or there could be options for the clans to agree upon. For example when the option to approve the transfer is made, a clan member could select either '3 days, 5 days, 7 days' and the gold they are required to send would be increased to cover the 'pay' for this period.
Finally, once this time ends a portion of the troops automatically transferred get transferred back to the original Lord depending on how many troops that Lord originally gave and casualties ect to the overall army ect. You would then have a time limit in that the rank 4 who demanded the troops cannot demand any more until this limit is over or if you redemanded troops again there would be some kind of penalty. For instance, perhaps the rank 4 having to pay a larger portion of the upkeep from their personal 'bank' of money on the second round of demanding and if they run out, it is at this point the troops run away, as this would reflect concerns that Earls and magnates might have when being asked to provide more troops for a longer period.
Of course this would require balancing of the original idea. You would have to limit the amount of rank 4's allowed depending on the size of a clan or add a new rank 5 that would essentially be a King. As in have all the powers of those below but could use this feature to gather an army, obviously there would have to be ways to 'over throw' this king if needed.
This is all very rough ideas I'm spewing out now, as it is 4:30 am here. But I was interested to see how such a system could be implemented in strat given the work that would be needed to implement it, as it was something many early countries had to do and it gave the individual Earl's and Magnates A LOT of power.
IMPORTANT EDIT:
I just saw the thing about allowing individuals to 'link' to someone. I think my system could be implemented with this. If the rank 4 who demanded the troops is approved by an individual, then that individuals entire force could automatically move to the rank 4 and the individual would have no ability to move it until this fixed term agreed upon was up or, perhaps they would have to stay within a certain range of the rank 4 who made the demand and so the ability to raid ect could be maintained yet when the main battle comes, the troops would be pooled. When this time ends they perhaps automatically move back to the nearest clan owned fief. This could be an easier way of managing the 'linking' idea without having to have constant communication.
Also it's possible that you would have to make it so that the rank 4/king received no more troops/gold automatically in your system once a certain portion of members had joined/transferred stuff to you and they were out of a certain range of the closest fief. You would also have to shift your tax % around a bit as well I think. I believe that in my system, these demands could only be made to ranks 2 and 3 because they would need to be the more active members. As such the tax rate for rank 1's should be higher to compensate for their inactivity, whilst perhaps the upkeep for troops in their rank be lower due to the fact they won't be able to maintain gold/troop ratios so easily.
Anyway, this is basically a potential solution for limiting large armies to rarer occurances of really big/important battles, encouraging smaller armies and individuals, yet reducing the amount of micromanagement/economic penalties needed to do it.
I apologise if that was long winded at all and not clear in places/a bit scatty. But it's late and I only thought of this about 2 hours ago