I don't have bibs, but I do have a pair of insulated pants - GoLite sold them a few years ago - and a couple of down parkas, one of which Jim has seen (same one in my photo).

Jim is right about an easy trip and exit. Yosemite is perfect for beginner winter campers. You get the experience without any real risk. As Tom Bodett used say in the Motel 6 ads, "once you turn out the lights, all motel rooms look the same" and that is true of snow camping. Up at Badger Pass, once the day hikers go back to their cozy hotel rooms or cabins, you are out there by yourself and the skills you need to eat and sleep comfortably are easily practised within a short walk back to the car (if you consider 2 miles or so, a short walk).