I would have never guessed. The instinct must be well intact in the hen. My 2 breeder hens (RN) are in an open cage similar to a flight pen, but smaller. 5H,4D,8L. Do you, in your expert opinion, think the openess would lend itself to too many distractions for a hen to rear it's own brood?
I have an inclosure that the birds can get under during bad weather, and have seen them dig nest-type bowls out of the straw I put in. They have also laid eggs in these "nests."
The only problem I see is that I feed and water everyday and that may disturb a brooding hen. A bit long winded, but I did quit smoking.