Well, it finally happened. The weather warmed up, and the chicks have moved out. Huzzah! They did have a heat lamp on at night, to help them get used to the colder overnight temperatures, but it blew out on the first night. Since then, they've been roughing it in their repurposed tub and doing well. Not that the house has been particularly warm for the past couple of weeks, and they haven't been sleeping on or under the heat plate for a week or so now, but still, it's different when you're living outdoors.
I made a little cabana for them out of an old rubbermaid tub, with a hole cut in the lid to allow the radiant heat from the lower wattage heat lamp into the belly of the tub. Lucky for me, I kept the cut out material and was able to block the hole back up after the lamp died. Most of the chicklets seem to have figured out how to gather in their new house, and they have enough feathers to bunch together and keep themselves warm even if they did decide to not go inside of the tub for the night. As you can see from the short video, they are pretty content with life out in the big world, lucky chicks.