I assure you, "the answer" is indeed not in official doctrine.

That said, there is a great deal of tremendous concepts, TTPs, thoughts, etc in official doctrine. The problem is one of context. Military doctrine on COIN is written in the context of how military forces conduct COIN warfare.

Change the context, and re-read the same doctrine, and you find that 70% of it is definitely worth hanging onto, it just needs to be rearranged into a new context regarding how military forces properly engage to shape and support foreign policy abroad in lands consumed in insurgency.