Because of the effect you’re talking about, the outdoor dew point is never above the outdoor temperature- so the air even indoors gets really dry when it’s cold

Because of the effect you’re talking about, the outdoor dew point is never above the outdoor temperature- so the air even indoors gets really dry when it’s cold outside, and you only need to keep the inside slightly warmer to keep this from happening. I am into sailing and often sail in cold climates without cabin heat- and find that my body heat alone is enough to prevent this from happening in a small sailboat cabin.