There are only two choices that I know of to reduce sweating - 1) Mechanical removal of moisture in the air and, 2) Ventilation. This last may be counterintuitive, considering that you are trying to stay warm. But you might be surprised at what slightly cracking a window and a vent can do for you.
Happy Camping! ///// Richard D.
2006 4x4 Ford 250 SD / 2007 Flagstaff 827 FLS
One very patient wife and one furry child who travels with us. Forty-two years of trailering and camping, and I still have a blast.