I did not want to kill the longbow the first turn, necessarily, I admit that.
However, testing proved that I could make him move away, simply by moving forces in between, then I could attack him with the Keshik with no river crossing and no elephant counter, on the other side of the river. I tested this extensively in a separate game I set up.
For the second stack, I did not really get any support for it. People did not want me to complicate things, yet, separate voices wanted to take out the longbow, but gave no option for taking out the keshik in a counter.
Yes, it was not that simple, as it seemed. Since I am now pressed to use the keshik across the river, in place of delaying the longbow kill one turn, I had to adopt another strategy. I now promotes the Keshik with Amphibious trait, and wait for city spears and the elephant to counter. Only option there is the Axeman with archery and cavalry bonus.
So, I sort of managed to delay the assault until healed, but failed to delay the pursuit of the longbow one single turn. This longbow would not move into the city with the plan originally laid out. And no one really cared about the elephant (someone wanted to sacrifice 2-3 axemen, axemen with 3-4 promotions).