Travel off-season
You can travel with a roof top tent all year round. To take care of your thermal comfort, it is worth equipping the tent with a third layer of material - thermal inner dedicated to a given tent model. It keeps proper air circulation once there are temperature difference between the interior of the tent and the surroundings, and additionally insulate ourselves from the cold and wind. This is must have if you travel off-season for all the tents besides Voyager PRO (which is 4 seasons tent).
External way to warm up
If you really like warmth, you can also think about an external parking heater. Easy to use and compact size, which we can always take with us. This season we discovered something really compact, perfect to pack into any car, easy to fit even in a small trunk.