Hi, Wow...my wife and I were just talking about all the effort I went to ...to provide plenty of nest boxes for our girls when designing our coops. First coop, pretty good size. 10' x 12', walk in.... houses around 30 girls. Built 4 very large , outside access nest boxes....the wenches use 2. Second coop for Bantams, 6' x 8' houses, walk in....living there comfortably are around 25 Bantam girls, so I built 6 roomy , outside access boxes....those crazy little "sweethearts" only use 2 of the 6. So from what I have learned about the chicken math on 4 per box is totally bogus. They will lay where they want....in a box, under a porch, on the floor, in the run, etc.... Just build/provide a box or two per 10 girls and you'll be fine. If ya get time, check out my photos of coops I have built and the extent I went to for giving them ample space for laying and you'll see what I mean. Spent alot of money and time and they don't even appreciate it. But chickens will be chickens. Good luck on what ya decide to do with your idea for nesting area.
Erik