Tails make good handles for quick transport. Know where you're taking the rat and get it there within a few seconds of pick up and you shouldn't encounter many problems. You can also try to hold babies you plan on growing out as future breeders a bit more than just changing day. I grab my breeders by the body and they have no problem with this type of handling - they just chill. Feeders get the tail treatment but are never held like this more than a few seconds at a time.