BUT my hypothesis is once someone fixes their head posture and can sleep on their back without ANY PILLOWS (which i have done), the crane should would perfectly. Anyone who has the crane, is this wishful thinking or does this sound practical?
I agree that with correctly forward grown bone structure it should be possible, and perhaps even optimal. Do you find it easy to breathe while sleeping on your back without a pillow? I find sleep apnea and heavy snoring unavoidable when sleeping on back, even after using pillows to elevate the head and neck.
It seems that even Native Americans - whose skulls neared perfection - didn't sleep without a pillow. Yet considering the evolution of the modern human it should be reasonable to assume that man spent majority of this lengthy period sleeping without a pillow, especially before becoming self-aware enough to start utilizing complex tools. All animals in the nature have their own proper growth ensuring natural sleeping positions that can be achieved without any extra props. It wouldn't make sense to believe that the modern human would've evolved to
need a pillow for sleep either. Instead, it was probably something that was picked up over time to compensate for improper structure and form.