It seems that each year we loose more and more colonies every winter. I pondered this issue for several years. The solution I came up with was simple. I would purchase a cargo trailer and customize it to accommodate my bees.
I started by removing the interior plywood and installing insulation to the walls and ceiling. Then I reinstalled the plywood and painted all surfaces. I then built shelves to hold nuc boxes, 118 of them. I carefully laid out the 1” holes I needed to drill for the entrances. Each nuc box had a 1/2” pvc pipe to allow for the bees to go out on cleansing flights. In the front of the trailer I installed a 30,000 btu propane heater and several computer fans to circulate the heat. I also installed solar panels and 2 180 amp hour deep cycle batteries and a power inverter. I then equipped the trailer with a mobile hotspot and temperature and humidity sensors and a dehumidifier. The trailer can hold an internal temperature of 40 degrees to allow me to feed during the winter. My nucs overwinter great. If you have any questions about this give me a shout and I will be happy to help you.