Progress update, and the final step for getting my chicks off to a great start --- I moved them from the plastic tote with heat lamp, into a much bigger brooder cage with a 12x24 heat plate. The temperature regulator arrived yesterday, so I was able to get this hotter-than-hot heater plate to behave and stay at 125-degrees. The day-old chicks seem to love it! I have it set with one end higher than the other, and they're mostly huddled in the center of it or exploring around the perimeter.