I'm not right there with you in your back yard, but I sketched window opening placement in BLUE, and Roost placement locations on inside in RED. The one higher would be the summer one , and the lower one would be winter if you decided you need to keep windows somewhat opened.
You are using...
To easily make a sliding open window, get some channel like pix below, plastic, aluminum, wood. Or make your own from wood on table saw. (if you can)
Channel will hold Plexiglas in place. Visit Home-center for their assortment.
You can make a window framed in wood, with Plexi for clear...
I know the roost bar needs to be above the egg box, however does it need to clear the top of the egg box?
In your design I see that your nest boxes are going to be pretty much on floor level. I would place a board across the front, to keep most of the floor litter from being scratched into...