Your set-up looks great!!!
For not too much money, you could use one of your hutches.
How about making it kinda like a playhouse coop. Enclose the bottom for a small run while they are locked up. You will have to cut plywood pieces to cover floor & doors. Make them removable for the summer (door covers). I recommend leaving the floor solid on one side at least, year around. I think it would be better to have the whole floor covered, but if you can't do that all at once, make sure you do one side. You would have to cut a hole in the bottom wire to attach a ramp going to ground.
Make sure you make a door so you can get to bottom area.
Put a roost in the side you want to keep covered, you can use one of your rabbit nest boxes for a nest, you will only need 1 for the amount of hens you want.
My chickens are always laying in the rabbit nest boxes we store on top of each cage when not in use.
Chickens love to scratch & play under the rabbits. They keep the smell down too. Our chickens keep our spilled rabbit pellets eaten, & scratch in the poo, so it doesn't get wet & stinky.
When talking about banty's. You didn't say what kind of bantys you wanted. Cochins & Silkies don't fly high at all. They are cute & friendly. They lay a larger egg than the Old English varieties (which fly extremely well).
These are just my ideas. Hope they help you.
Jean