Yeah, both the timeline and blood type work against the Rayleigh-Shakky-Mihawk theories. I do believe the betrayal Mihawk experienced is connected to his mother, but Shakky seems ruled out at this point. The mother was still likely of royal blood.
Potential Backstory:
Mihawk's drive to seek power and become the strongest, even as a child, may have originated from his wish to protect her. With new ambitions ignited by the Roger era and a desire for greater strength, Mihawk set out to sea, entrusting the Marines with her safety. However, they failed him, giving rise to his distrust of others and his hatred for the Marines. This ultimately led to his vengeful hunting of them, and he became known as the "Marine Hunter."
Through his rivalry with Shanks, Mihawk first saw the quality in Shanks that he would later see in Luffy, i.e., making people want to help. He came to consider this the most formidable power of all because, despite reaching greater heights in individual strength, his mother might have been saved if he possessed that quality. Once his anger had quelled and his ambition achieved, he took on the warlord mantle to live a quieter life.