In camel, a mild internal rotation of the legs is recommended to keep the sacroiliac joints stable, which will favor hip and spinal extension over sacroiliac counternutation (which is what happens when this pose is felt “in the small of the back”).
It can be very challenging to find a healthy extension of the spine at the base of the neck or the top of the thoracic spine. It helps to focus on releasing the sternocleidomastoid using the eccentric strength of the deeper anterior neck muscles to stabilize the weight of the head. Additionally, in many people, the upper trapezius muscles form a “shelf” in this position that can provide a resting place for some of the weight of the head.
Camel is an intense stretch for the digestive system, especially the esophagus.