...For those of you that have used hardware cloth are your chickens completely enclosed in a coop/run situation? ...
I can't free range where I am due mostly to the fact that there are too many ways for it to go bad (children leave doors open, dog gets out, cayotes, coons, bald eagles, hawks etc). my inner coop, coop and run are completely enveloped with hardware cloth but if I expand further, I won't necessarily envelope the additional run(s). I think the key here is keeping the rats from getting to the feed and eggs, which means having the ability to close the door at night on a fortified "inner coop" where the feed is stored, where the food dispensers are located as well as the laying boxes. this inner coop needs to have no more than a 1/2" gap anywhere around the envelope, especially the door, so narrow to prevent an adult rat from getting in. a baby rat getting in would be a temporary situation and not worth worrying about too much, it is very unlikely to cause real issues. rats are mostly nocturnal until their population explodes and they become sloppy, they can have up to 22 babies every month or so and those babies can have babies within 6 weeks. if you are seeing healthy rats during the day it's a bad sign, IMHO, likely that they have an unlimited food source and are having a hay day. If you can close the door on a completely secure space in the evening and open in the morning, you will likely take care of the lions share of the problem. an automatic door makes this much easier. with large acreage there is no way to completely eliminate the rats and that is not my goal. my goal is to keep them out of the coop where the chickens eat and sleep and lay eggs, keeping the rat population down to a "normal" background level. actually I should also say that my #1 goal is keeping the rats out of my house, rats in the home cause severe issues and in that case I would happily resort to poison to swiftly eliminate every single one. I had a friend build a coop right next to her house and naively leave the food open and the feeding area accessible, by the time she noticed the stink coming from her walls it was too late, she had to get an exterminator that removed over 100 rats from her walls, they did a lot of damage and it cost a lot of money.
If I had more land and needed to secure a large area, I would just hardware cloth the area to be enclosed at night and run electric fencing around the perimeter to keep the other larger critters at bay.