What is the critical hand placement adjustment needed to successfully apply a rear-naked choke when an opponent has a strong chin tuck?

The critical hand placement adjustment needed to successfully apply a rear-naked choke, a submission hold that restricts blood flow to the brain by compressing the carotid arteries, when an opponent has a strong chin tuck, a defensive posture where they lower their chin to their chest to protect their neck, involves 'threading the needle' with your choking arm. The primary goal is to bypass the chin and position the choking arm's bicep and forearm directly against the opponent's carotid arteries. Instead of attempting to force the choking arm directly under the chin, which is often ineffective against a strong chin tuck, you must first establish a deep grip with your non-choking arm around their back, pulling them tightly against you. This minimizes space and reduces their ability to defend. Then, with the choking arm, focus on pushing your hand deeper behind their head, aiming to get your wrist or forearm *behindtheir jawline, almost as if you're trying to reach their opposite ear. This allows you to 'thread the needle,' circumventing the chin and positioning the choking arm in the correct location to apply the choke. The second hand then clasps the choking arm to complete the choke. Without this adjustment, the chin will block the pressure from the carotid arteries, rendering the choke ineffective.