I always have my local shop scour their box freezer for the smallest of the small-fry rats they have on hand. And I just keep those little sad runts around for when my snakes want that 2nd helping or a midweek snack. They can easily digest it as long as you're not pushing their primary meal to some size extreme. I've always had better success keeping my snakes on feed with the continual little rat snacks and 2nd portions here and there rather than giving them one ginormous taxing rodent. They can easily not be in the mood for a massive rat but will almost always go for the warm rat snacks. YMMV