Hey Mike–I’ve not been in SGW yet this winter (surgeries, hopefully soon!) but:
historically speaking, Sky High approaching and into the switchbacks on the E-NE side of San G is among the last areas to melt out and return to a non-mountaineering zone in the range. Whereas Vivian is primarily S-SW aspect and gets alot of sun, those Sky High switchbacks stay shaded into mid- spring, thus usually icy-dicy all day.
Following 2019’s big Feb snow events some (strong!) pathmakers smartly bypassed these switchbacks by breaking trail up and over the adjoining ridge. Study the topo and note the steepness of the drops in this area.
My vote for safely summiting SG in Feb remains Vivian (or Momyer/Falls Creek if you’re into some mega-mileage!); via SF/Dollar a more distant second but only with mountaineering training/gear under belt and onhand. Not trying to be alarmist but a hiker died last winter on the Dollar trail…so whatever the route, do take supreme care this time of year. Looking forward to your upcoming TR!