Our nesting boxes are on the outside. It really does give you more room. Our coop was originally designed around bantams, so when we decided to get the big girls were had to make some changes.Put the nest boxes outside the coop, on the east or north side so they don't get hot in the summer. That will free up some floor space.
Here are some pictures of our setup and what we had to change.
One of my favorites, 6 fluffy butts.