Camping in Sequoia in the winter is a wonderful experience. The first night, the campground had about 30 people total there, and they were quite spread out. It was quite cold (15 degrees), so there wasn't too much noise from people running around. Once it snows, however, people leave, and you'll be there virtually by yourself.
The trick is to set up your camp, eat, then go to Waksatchi Lodge and warm up until about 10pm so you can go to bed and not wake up at 4am, waiting for the sun to come up while you're freezing.