Our pack weights for those trips wasn't much different than it would be for solo backpackers on warmer weather trips. I took advantage of hiking as a couple to minimize pack weight. We were in excellent backpacking shape and we didn't have any real nasty winter weather-- no snow storms. Being out 2 or 3 days at a time you get a pretty reliable weather forecast.
We didn't stay up in the evenings in the cold weather and didn't have the clothing to. We had light insulation to hike with and depended on tarp/tent and sleeping bags to stay warm when the sun went down. When we selected a campsite in cold weather we kept moving, got dinner cooked and ate, and got into our sleeping bags before we got cold. Mornings were the same way, we cooked and ate a hot breakfast and was on the trail within an hour of sun up.