Thats over 24 hours for digesting his last meal. He should be ok. You could also put a towel in hot water, ring it out, roll it up and place it along the outer edge (outside) of a temp tub to simulate a warm spot in a pinch.
I keep a box of the 48 hour heat packs on stand by with a pretty large UPS. We tend to lose power often in the gulf coast.![]()