Good question! Our major use is in winter. Previously to our daughter and family moving to Missouri, we would take at least two winter trips to enjoy a week or two of warm weather. Each trip started with a killer cold night in Oregon and ended with the same, enroute each way.
What we did was bring two sets of sleeping bags, a warm weather set and a cold weather set.
Now that we include Missouri on our itinerary for Thanksgiving, I have installed a vented propane
fireplace that can be operated at night. That works reasonably well even with the limited insulation installed in a Scamp
I removed all water tanks and apparatus, so there is nothing of importance to freeze up. We use gallon size bottles in the trailer and carry the bulk of our water in our tow vehicle. The sink now drains into a portable 2 gal container below the sink. The evening before settling in for a cold night, I get the coffee pot ready so all I need do is pop out of bed, light
the burner and pop back into bed. By the time the coffee is ready, the trailer is warm enough for human consumption. :>)
It will be interesting how others cope with the cold!