It would be cruel to keep a chicken in such a small enclosure, they need more room, which most people supplement with an outdoor run, and even better free ranging.
I applaud you for acknowledging this fact yourself, with your own solution, the chicken diaper, which will turn your house into their run.
I'm glad you realize 8 square feet is only the bare minimum for a sleeping coop for two birds, but in addition, they also require a run, if you want to treat them with more respect than a factory farm, which I sense you do.
I don't think chickens are suitable for indoor habitation, but you're going to extraordinary means to achieve your goal, which may not be in the best interests of the birds themselves.
However, unsuitable it maybe for a large bird like a chicken, the beautiful cage you've built, would be a great habitat for smaller birds, a job well done!
We all have to deal with the reality of our particular circumstances, in this case the size of your cage, and the fact they can't be outside.
I should have asked, can they be outside? Do you have a yard?
If not, you have a choice with your cage, a very poor chicken habitat, or a knock your socks off terrific habitat for smaller birds.
You seem determined to have larger birds though, any chance you have a friend, or friend of a friend, who has a yard you could use for an outside coop, maybe in exchange for some eggs?
Heck, I even give my neighbor a dozen eggs every couple of weeks, so she won't resent my little flock wandering into her yard occasionally.
Life is choices. It's hard, but things always work out better when we try to consider the other guy too, who's going to be impacted by our choices, even if the other guy is just a chicken!
Good luck!
