For the ants, you could try putting the bait in a moat - ants can't get across water, but it wouldn't stop the rats.
I have chickens that backyard free range during the day and sleep in a mini coop.
For security, the coop is raised on wheels so preds can't dig in, and it is all plywood/hardware cloth, one door with a key lock, and a thick lucite guillotine door now with auto door. I have never had a break-in. I agree with everyone else that hardware cloth is a gift from the heavens.
I love the auto door (ChickenGuard, which used to be much cheaper...), it has settings for timer or light, but I agree a dawdling girl can get locked out (just happened), and I understand the risk that an early pred could get in.
I always worried that a pred could paw open the door, but I have not seen anyone report that on here.
It's great you have the cam to learn the routines of your local preds. Mine don't seem to operate early, and that helps to inform my choices.