I actually prefer the general ideas behind Exalted's mass combat: the leader of the unit is the baseline, the unit then essentially modifies them and allows them to participate at scale. So a unit led by a fighter would have the fighter's attack bonus +/- a mod based on how well equipped the unit is, and dmage that starts witht he fighter's damage +f(x) based on the size of the unit. It should look like Dynasty Warriors (one big hero mowing down crowds of mooks, while followed by their own crowd of mooks) rather than anything realistic.
Why is this good? Because it keeps the story about the main characters, and lets the players use their pc's rather than brand-new statblocks that work differently. It makes mass combat an extension of the game, rather than a whole new game tangential to the regular mechanics.
Downsides: obviously "realism" is not a priority here, so this will simply not work for some people. Also it doesn't really account for two pcs in the same unit, though I'd just not do that rather than try to figure out how to make it work.