I agree, no dumb questions. Not asking is the dumb thing. To me this one isn’t all that strange. Adding heat sinks to incubators is talked about one here every now and then, especially by people that experience regular power outages. Also if an event like an ice storm is forecast that can cause a power outage, you might want to do something like this as a precaution.
I don’t know what your turner looks like, can you remove some rows? A common method of adding a heat sink is to fill a zip-loc type bag with water or use a water bottle. It’s also a good way to maintain temperature in case of a power outage but you can still heat water, just don’t overheat your incubator by adding water too hot.
I don’t know how much a heat will help stabilize temperature, it certainly will not hurt and logic says it will help. In most circumstances it is probably unnecessary. I don’t completely fill my incubator and do not add a heat sink. I just hatched 23 of 28 eggs in an incubator that could hold 42 eggs.
I think one thing that is much more important in stabilizing an incubator is the relationship of the thermostat to the heat source. It needs to be close enough to the heat source to shut it down before it overheats yet far enough away to pick up on when the incubator cools down so it needs to restart the heat. This is a common problem in homemade incubators. Also put the incubator in a location where the ambient temperature stays pretty constant and not where in any breezes (doors or air vents) or sunlight (windows) hits the incubator.
You may be overthinking this but at least you are thinking.
