Yes there are multiple ways of keeping enough men in your party. But there are instances where you should not want to use a workaround because the other lords have the first pick. I think that moving recruiting for the AI nobles on leaving instead of entering will keep the current system intact, but will give te player the first pick.
Besides the OP point:
I would like a system where while you are on campaign, you can order a companion/clanmember to gather x amount of men from x garrison to refill your party. The same with supplies. With a specially made caravan or by a regular allied caravan.
Of course they could be attacked while on route.
I always recruit the prisoners on an extended campaign, but I don't actually like it. I like the look of a more homogeneous army where my units look noticeable different then the enemy.