I have a chi mix, whom I will just refer to as the “Chiweasel,” who obviously hates the cold. He was a rescue from Texas and currently lives in Virginia. He gets to wear all the sweaters and pajamas in the winter, and we are using booties with trial and error. He is house trained and not pee pad trained, every “pee pad” trained small dog I’ve met seems to think that everything is a pee pad.
Last winter I tried a kiddie pool in my unfinished basement with mulch and fake grass- he was not fooled, but our winters are reasonably mild and we usually manage potty outings even in the worst cold Virginia can throw.
Hypothetically, is it possible to re-train a dog to use something like this? If, hypothetically, I were to move somewhere even colder, like Montana or Wisconsin, he is likely not setting foot outside the door if it’s 20 degrees below zero.
How do people manage small dogs in below freezing temps??
Why is a little dog any different than a big dog with a short coat? I have a big dog who hates the cold but she can go out to do her business. I think your small dog can too if you put a coat on it or something? You may have to go out with her 
Our temps go as low as -40 at times and my little maltese managed well. The depth of the snow was a bigger problem than the cold because his little legs were so short.
I would not consider training an adult dog of any size to use pee pads for this reason alone. Your little chi should be just fine.
Mine never hesitated to go out on cold days, but he didn’t like the rain lol! You definitely need to keep outside trips very brief, but it’ll be fine
Do you feel sorry for him because he’s so tiny and assume it is too cold for him to go outside or does he act like it? How serious do you take him?
Sounds easy, but I mean I get it, some dogs just refuse to cooperate and will stare frozen at door and just not potty, ever, I guess. So where does he historically do his biz when it is “too cold” outside and refuses to go outside? If you are aware of issue, especially enough to ask for work arounds, then I assume he has already established a plan B. So if he whizzes in the living room corner or craps on extra bedroom floor, then try setting up the giant litter box or whatever in those places. Make it dog friendly, give him a variety of options, and reward for using them. That’s hard to conceptualize sometimes in these cases, because I assume you would actually like for him to do his biz outside, all the time, like a normal dog…but if you are willing to compromise then be prepared to train him it. That includes treats, etc, just like you would do with any other dog to train it to go potty outside. Same same for inside.
I’m not sure I would be so worried to use “pee pads” for him at this stage. He’s a mature dog who knows how to roll, so it might not be a problem. And so what if he does? He might not get the “only when its very very cold” part of the program. He’s tiny and you’ve already accepted that he should potty inside at least some of the time and take responsibility for cleaning/upkeep, so it might be worst thing ever.
My vet assistant has two chihuahua types and when the snow gets too deep for them, she shovels out an area near her back door and puts straw down so their little paws don’t get too cold. She even stands a log up so the male has a good place to mark his territory. This has worked very well for her. I have a mini rat terrier whose legs are like 3" long, and he’s slick-coated. he loves bounding through the snow with the big dogs, but prefers to do his “business” under the camper where there is no snow. 
