Syrian hamsters don't live together peacefully. I think you'll run into territorial problems when they mature.
Mice are smelly but rats are big. . .I don't know which one I would choose to breed if necessary. But not hamsters! Maybe gerbils; they live communally and aren't too smelly.
Gerbils are very capable of handling themselves against snakes. They have big back claws and will attack snakes.
Stick with mice. They aren't expensive. They breed like bunnies. They're easy to kill.