Need tips and experiences for first time winter camping.

This may be obvious, but bring a good rubber walk-off mat to wipe your feet on before climbing up into the camper.

We have done a lot of snow camping, but never below 9 degrees, and usually in the mid-20s. We boondock -- no hookups. A down comforter is all we need at night -- no heater except at shower time. But a caveat -- our trailer is very well insulated -- thick styrofoam in the walls and ceiling. If your camper is not well insulated, it will be a much more rugged experience.