I will add the Mr and Mrs Monkey did build a nice looking setup.
Is there a door to get into the coup other than from the pen?
A door into the coup will make it easier to clean out in the winter.
TSC had good rubber boots, get some, it will get deep with mud in the winter.
Water heater from TSC is 30 to 40 dollars.
Find a cookie tin, round is better(I got 4 from the Good Will store).
Get some blub bases, 1 for each tin, I had 4 waters to keep from freezing.
Mount the blub base inside the tin, I use a 100 watt rough service blub.
Tie it with wire it to the bottom of the water pan, plug it in, my water was wet all winter,
even them very cold days and nights.
You drill the hole for the wire in the side, seal it with clear silicone, at night you can "see" the light.
I built 4 for the price if 1 of then store bought things. LOL