Okay, here comes my totally no expert advice, well it isnt even an advice really, just how I very unsofisticated did it. I used to breed and train horses, and had shetland ponies for my children, we did pull sulkies with them, so I have experience lol..... just not with dogs.
However, we have a Siberian Husky, a rescue from the humane society, we live in NC, so not a whole lof of snow here, but the winter before last we had a bit, a friend of mine had a pulling harnes, so we put it on him and off we went with the snow hmmm do you call it sled??? you know the little kind they sit on the bottom in. I know from having worked a lot with dogs in other respects and horses that, that was the absolut no no thing to do, but hey it worked, he was happy as a lark and my then 3 year old had a blast. He was having the time of his life. After that I have not done any carting or pulling, but now when I talk about it, it would probably be a fun thing to do, even without snow, especialy since he enjoyed it so much.
Marit