I'm not sure how much you need to get you through the winter, but there are some spots online where you can order dubias in big quantities and not stress over breeding them.

Another option would be to place a smaller tub inside a larger tub and place crumpled newspaper, foam insulation, packing peanuts etc around the inner tub to insulate.

I recently switched from crickets to dubias and I love using the roaches so much more. They're quiet, don't smell, last longer, easier to hand/tong feed, and I swear they are cleaner than crickets, and THEY DON'T ESCAPE which is a big plus.

I split mine up into two groups, feeders and breeders. I have the breeder box on a heating pad, and the feeders by themselves in a fairly cool room, and the feeders have been fine with the cooler temps.