I use a 100 watt ESU Red Heat lamp to thaw all my rodents. I suspend it about 10 inches above a plate I set the rodents on. It only takes about 2 hours, one hour per side (flip them over to make sure of a even thaw and heat transfer). I then use an infrared thermometer to check the temperature.
I just do something else while they thaw, like watch tv or work around the house.