I know I have seen at least one photo of a corn snake on real snow, and I want to say it was taken by the Love's, but am not 100% certain. It was under special circumstances, I believe, but my mind IS working on a potential solution for you if you are not in a big hurry to get your photos.
Having grown up in the Catskills in New York, I know quite a bit about snow. I also know how cold it can get down here in Florida for our native corn snakes. For your photo shoot, watch your weather patterns and wait for those warm sunny days during the spring thaw where there is still snow on the ground, even if it's in patches, but the temps are nice.
A week or two ahead of time, stop feeding the corn snake(s) you plan on photographing. It's not going to hurt them. Then on that nice day, get a "warm" water bottle ready in a box and blanket set-up, take your snake outside and get your photos in the snow, spending only a minute or two at the most with the snake in the snow. Then, put your snake in the blanket/box with the warm water bottle (barely luke warm...don't want to go to extremes and hurt your snake) to let it warm up a bit before continuing with the photo session.
The snow will be 32 degrees at the coldest with air temps most likely in the 50's, easily tolerated by a corn snake especially if only in contact with the "extreme" cold for only a minute or two. It takes a longer for the body temp of the snake to cool to that temperature so the snake actually never gets that cold. Will it be a little uncomfortable? Probably, but I wouldn't think it would be nearly as bad for the snake as it is for me going outside on those frigid mornings to get the paper.