Are you prepared to have around 20 rats in that one ten gallon tank? That would be incredibly unsanitary and not to mention would be a very bad situation for the rats themselves. If you are only feeding one snake, it would be more money-conscious to just find a good pet store that sells healthy feeders and either buy a few adult mice per week(one sex unless you want more) or buy one rat pup per week. You would save yourself alot of money not having to properly(notice I said properly, now...) feed, house and then feed off 20+ rats if you do end up breeding them. I have 17 as pets and I spend around $70 on their food(not including the $20 50lb bag of lab blocks that they get sometimes) once every 2-3 months.

A ten gallon tank is big enough for one female rat and her babies for maybe a week or two. They then should be moved to a multi-level wire cage or big tub as the increasing size of the babies causes more ammonia to be produced, not to mention crowding them in a 10-gallon tank doesn't allow for proper exercise that they need to be healthy.

For one snake, a pair of rats would produce babies too rapidly for you to even dream of using them all before the rats get too big. You would have to euthanize and freeze them(not knowing if your snake will consistently eat f/t prey) or you could sell them to the pet store.

I breed mice(occasionally) for my snakes(6 now) and rarely do I have a female eat her babies. I keep 1.2 in 10gallon tanks for a week or so and then sometimes I take out the male, but most times I leave him with the girls for a consecutive breeding(just depends on how many I have in the grow-up tanks. I have about 6 tanks now with varying sizes of mice(separated by sex of course). I am feeding them Mazuri Rodent blocks that I get at the feed store. A 50lb bag is $20 and it lasts a good long while(3-4 months). Sometimes they get a handful of Science Diet Canine Maintenance dog food(since they are kept at school). Other than that I just clean cages once a week, feed and water, etc. and my job is done. The guinea pig at school takes longer to take care of than those mice, LoL.

Just some food for thought(literally).