I hear you - that design is the result of a lot of sleepless nights on my part! Glad you can use it too!
That's about what size mine is too. We added a 2x4 running along the floor and screwed it into either side of the coop. There are three panels made out of 2x4 squares with hardware cloth...
I was in this exact situation a couple of weeks ago.
I built her a ground-level enclosed pen with a little wooden house inside it. I moved her in the late evening when she was sleepy. At that point she'd been sitting on the eggs a few weeks. In my case, she had been disturbed from her nest...