Two backpacks? No way, two sleeping bags? No way. Two bics, no way, I always have three and waterproof matches in zip lock.
What Ppine said is spot on. Go out some night with just these three things and see how little discomfort you really feel. It does wonders for your self confidence to know you can curl up in a snowbank (providing you were well dressed for daytime snow conditions) and still get some sleep.