I hike there in summer and (though not for the last couple of years) snowshoe, X/C ski in winter. I'm a crap X/C skier and would advise snowshoes if going from Guthega. Often the car to suspension bridge is crap for skiing due to patchy snow. Just straight line it from susp' bridge to Blue Lake on snowshoes.
Sorry to sound preachy but:
I hike there in summer, so I a beg of you to pleaase camp in an eco-friendly manner...
Try to find soil to dig in for crapping (camp on east shoulder of little twyn' and head to tree line - though not too close to creek/rivers).
Remember that snow cleans better than paper - try it.
Take extra bags etc for all rubbish and bring it out blah blah blah.