Nyt had an article from 1988 about bout a US army doctor who had a treatment that works. Google it for details on number of sessions length of time. I recall they had people strip except for feet and hands and those were warmed in water, dried placed in gloves. then they went outside naked except for cozy wwarm Feet and hands. Basically tricking the body to think the extremities were. Warm so the trunk core must be fine and it would open the blood vessels to hands feet. Eventually the body would not cconstrict hand feet blood vessels at cold contact. Takes some acclimation but worth a shot.