Thank you for helping this little rescue and taking on the issues that some of them have with an open, loving heart. People who help these dogs, little creatures who've known nothing but cages and deprivation, who are so needful of real, responsible love, a regular schedule that includes trust and confidence building activities, lots of exercise, play, fun, training, inclusion in the family, stability and sometimes infinite patience. They are worth all the effort and you are an angel for taking a former mill dog!
For the short periods of time your dog will be crated - when you are too busy to supervise her out in the house, have to run an errand during housebreaking training, all a dog needs is a crate big enough to stand up, turn around in and still have room for bedding, water, food and a poop pad for emergency situations. Too big a crate may encourage pooping in the crate rather than training them in holding their bladder/bowel.
The rest of the time, your dog should be out living its life with you and learning how to be a real dog.