I've heard that you shouldn't bathe them before a shed, because it will take away some of the oils in their skin that help them shed. I would just get the digital thermometer/hygrometer and up the humidity - the towel and changing the substrate should do the trick - and make sure that she has access to fresh water. Only give her a bath after she sheds, and only if she doesn't shed completely. Or if she has a bad shed, you can put her in a wet pillowcase for a bit instead of a bath.
As for the rats, if they're as thick as she is, then that should be fine. There should be a slight lump right after she eats. Rat pups are typically 21-30 grams, weaned rats are 31-45 grams, and small rats are about 46-80 grams. Our boys were on small rats by the time they were 8 months, which is why I was confused when you said rat pups.