Where do you live, and what temperature does your house get at night? If it stays more temperate/warm, then I would say it is possible. Personally, I am no fan of the small tanks - so I would suggest the largest of what you are considering (5 gallons). I also suggest that you be sure to cycle it appropriately first. Other than that, the shrimp and the moss will work fine.
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Snails are my friends 
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