We do not have a diesel heater in our van, but we are able to keep cozy during the winter months camping with the following tricks:
Our van has thermozite and ultra touch denim in the walls and a cork subfloor. We use insulated window covers from Moohah Creatives (code SOWEWENT10 for 10% off). The window covers are one of the most significant ways to manage heat loss in the winter, plus they act as blackout shades to keep the van dark.
We use cooler weather sleeping bags instead of just blankets/traditional bedding as these offer much better warmth.
In addition to our sleeping bags, we add a heating blanket underneath all of our bedding on low to cycle on and off throughout the night. If we use our sleeping bags, the lowest setting is adequate to keep things cozy below freezing.
We wear thermals, puffers, and hats in our bags.
We cycle this mini electric space heater (200 watt) on and off throughout the night. We can’t leave it on continuously because it will drain our house battery, but it’s good for taking the edge off the cold air around our faces when its VERY cold. We do not use the battery bank mentioned above because it will run that battery down too fast. We use our house battery which is a 100 Ah battery.
Before we go to bed at night we will turn our van on and run the heat to warm up the cabin. This helps give us a warm starting point, the insulation and window covers aid in maintaining that heat, and then the temperature will slowly drop over the course of the night.
Last, but not least, snuggling helps when all else fails!