Around the age you quoted people will start to be having them outside more.
But I do see why you would be concerned for the low. There's nothing wrong with trying to have no losses to your flock.
You can try to be aware of wind; wind can affect the real temperature a lot. You can also make sure the nest area has fluff and cover for them to huddle down in (but beware of fire hazards if your heat source produces a lot of raw heat). (In mentioning the wind, I don't know if your coop is fully closed off from it.)
You can check on them to be sure it will safe. Try to find a time or two where the temperature will be low for a bit, but when you can check them while you are still awake. And do this a few times to be sure it'll be fine. You can also increase feed a percentage amount for really cold or wet days. You can check them every few hours while you are trying this out to make sure it will work; but plan ahead to watch for what kind of reactions you will try to be spotting to be sure if you think they will make it through the night. You can also test if they are still lively or weak while watching them have their first few nights outside. If you plan to be ready in case you have to move them back inside, you can be ready for this just in case, but still try to make a go of having them out but being prepared.
Have you thought about if you know how to spot a weakened chick/duckling, in attempting their first nights outside?
