Good Luck with that.
I have two free range hens that run around the barn. One of them lays in the nest box I put up in one of the horse stalls. The other insisted on climbing through the feed whole in the horse stall to get into the walk way to lay her egg on the hay bale. I tried everything. She was very persistent. I eventually blocked the wholes, then she layed on the stall floor in the corner. So I put a next box on the floor in that spot and she started laying in it. Then I raised it off the ground and now she uses the nest box on the wall. Mind you it is right underneath the other one, but she will not lay in the nest box if there are wood shavings in the nest box. It must have straw.
If I put in wood shavings, she goes back to laying on the floor.