We travel mostly in winter. Living in Washington state and having family members in Missouri and California, we make that circuit, usually around Thanksgiving time or Christmas/New Year time. Then, being retired we take several weeks along the Gulf Coast, then west to California and finally back home. So you get the picture -- we prepare for both cold and warm weather.
We take warm weather sleeping bags and cold weather bags. When in cold weather, we are "on the road", so when we make the bed into a dinette in the morning, I take the cold weather bags to the tow vehicle and lay them out loose. This allows them to dry out and air out as we travel.
In the evening before retiring, we heat some water and use it for hot-water bottles. This especially helps with the initial cold shock of getting into a cold sleeping bag.
Also before retiring in the evening, I stage the kettle filled with enough water for morning coffee on a burner, along with the match box, coffee cone with fresh filter paper and coffee tin. Then, in the morning, I can pop out of bed, light
the stove burner under the kettle, light
a small Coleman portable catalytic heater in the bathroom and pop back into my sleeping bag in about a minute. When the kettle starts to boil, the trailer is toasty warm for getting up and going.
Even during the warmer parts of our trips, we do it the same way, even to bringing the sleeping bags to the tow vehicle. One reason for this is the open sleeping bags hide our stuff that may be "eye candy" for someone of questionable honesty.
I could also mention my propane fireplace, but that isn't something that most on this forum would have much interest in.