When I was feeding F/T I did as everyone else mentioned. But one thing I did was to keep them on warm water while time I'm feeding, and feeding sometimes takes 1.5-2 hours.

I would get a large Rubbermaid container, put a few inches of water in it. Get a fishtank heater and turn it on full power, older styles work best. Next would be to put the rodents in smaller Tupperware containers with paper towels in them, and float them in the water with the fishtank heater. And every little bit I would flip the rodents over to keep them evenly warmed.

This has worked really well for me to feed a large amount of snakes and keep the rodents warm while not cooking them.