if i were you, i wouldn't waste a perfectly good tank on snails. you could buy a cheap 10g rubbermaid bucket, put it in a warm place, even the basement or a heated garage, and run a filter on it. then the snails have more space and you can reclaim the 2g for a fish and make it look nice. snails are pretty tough, when i moved i did exactly what i just said and they were fine. they don't need it too warm, just as long as they don't freeze.
run a second filter on the 2g for a week or so, then when/if you move the snails you'll already be cycled.
you can easily make it look nice from above with gravel and plants, like a mini-pond, or just leave it bare and float some plastic plants that eggs can be attached too. if you don't worry about it looking nice and leave it bare it's much easier to clean when needed.