Casdon
I’m planning to cook the evening meal at lunchtime, and warm it up in the microwave at 7 when the lights come back on, that’s when we normally eat anyway. If the power doesn’t come back on, I’ll reheat on top of the logburner, but you could probably do the same with a candle operated platewarmer, they are very efficient.
I would strongly advise against re-heating anything on a plate warmer, as I doubt the temperature will be high enough to kill dangerous bacteria and vira. Most need at least 70 degree centigrade to kill them.
If you have a food thermometer, I suggest you try heating a dish on your plate-heater to see how long it takes to reach a safe temperature. In the professional kitchens where I have worked, dishes being kept warm on a plate-warmer were the first thing any sanitary inspector who turned up at lunch time checked, and usually told us that the food was not fit for human consumption , which lead to a fine.
Reheating on a log burner is a better option, but it takes far longer than heating something on an electric hob, so put it on in good time.