U_Stormcrow
Crossing the Road
You're considering roost height relative to window height, but I recommend putting them a little higher because of floor height: if the chickens can easily and freely walk under the roost bars, they can make better use of the floor space in the coop.
I agree about skipping poop boards. There is not enough total height to stack floor, space for birds to walk, poop boards, roosts, ventilation, roof.
In view of NatJ's comments, I will defer to his experience on bar height. In my run, plenty of birds go under (and sometimes rest/nest/play under a 275 gallon tote I have to store water, whose bottom rests on cinder block - just 8" off the ground - but in my hen house they walk around bars which are higher up. I can't explain it, won't attempt it.