You could do that, though I prefer to separate the feeders by sex. Breeding a small number of rodents like a 1.3 group won't require a rack though tanks are bulky and IMO hard to clean. They also do not provide good ventilation. You could make one of the rodent tubs in the DIY section. Those would be cheap to make and work great for rodents.

And tomfromtheshade is right. Wean the babies at 3-3.5 weeks old and separate them by sex by 4 weeks old.