I use the water trick as well. I put the rat in a bag to keep it dry, squeeze out the air as best I can, then put that in another bag and fill that with hot water. Leave it there for about 25-30 minutes, then drain and refill the bag with the water on pure hot to get the temp up(Pure hot the entire time makes for bad thaws and bloody rats i found). I use the bag instead of a bowl because the bags float and you get a hot/frozen side thing going unless you constantly flip it.
I'll sometimes try putting the rat on top of the cage under the heat lamp after to scent the tank a little, but nothing's been working lately.
What do you mean by bad thaws? I think I might have over heated my rat last nite. What are some ways to know that I overheated?