you should get some winter experience or take a winter travel course prior to trying san g in the winter. The best route is up the north face from south fork. Vivian you will not be able to follow a trail, so you need to navigate. snow shoes suck for winter conditions, you will just sink in the powder, and its steep off trail up hill, not fun. skis or a splitboard is the best option for traveling over snow, most of the day up, then fast descent down. then you need to know about avy conditions. the southern aspect of Vivian will melt and refreeze so then you need crampons and ice ax. going up the north face is direct and easy to navigate and if there is snow all the way to the parking lot that’s an added bonus. beware the top of the north face can get wind stripped and firm/icy at the rollover at the top. ive done both day and overnight trips in winter to san g.