So I'm hoping I can find something on craigslist that I can modify to keep the birds safe. I'm thinking the dog kennel might be the best option. Still figuring out how to attach it to the coop is still an issue. I'd hate to put the coop inside and lose that space... but that might be the only option.
The easiest way (especially if you're not handy) is to put it inside the kennel, even if it eats up space. Some kennels are modular so if you think that'll take up too much room, maybe you can get 2 kennel kits and double the space. That way the chickens get extra space and the coop will stay well secured without having to figure out a way to attach things.