Hwy. 46 that takes you to the TH of SS is closed till the summer. That means you will tack on an additional 4-6 miles. If you were able to park at the TH you are looking at a 12mile round trip when doing the South Side.
Avy danger is high right now. Yes it will slide up on SS.
Avy forecast: http://www.nwac.us/products/SABSEA
Weather: http://www.wrh.noaa.gov/forecast/MapClick.php?minlon=-122.11&maxlon=-116.45&minlat=43.57&maxlat=47.67&mapwidth=354&site=pdt&map.x=36&map.y=330
Most people save SS for the spring. However, if you don't have a sled, you might be able to convince some slednecks to tow you to the Forest boundary line.
Good luck
Dave