I don't trust rats either...which is why I feed them to my snakes. As was said, get the husbandry right and feed her large adult mice for a little while until she is eating consistently and is happy with her environment (usually indicated by her spending all her time in a hide). Then you should switch to rats unless you want to feed multiple mice when she gets bigger. It's much easier to feed a single rat to an adult BP in the long run.
Congrats on the new BP! She is very pretty.