I know your pain... I had a client dog who had KC during his stay. When he got here, no symptoms. A couple days after, the coughing started :( They are usually contagious for 10-14 days. Most vets won't even prescribe medication for it unless you're seeing green snot/runny eyes type stuff. Most dogs can fight it off on their own, but usually when the green snot comes out to play they will put the dog on antibiotics (The dog staying with me needed the antibiotics).
Your pups will most likely have a cough for a while after they are no longer contagious (Like after we get better from a cold, we are no longer contagious but have that annoying cough that doesn't seem to want to go away), so don't be too concerned if you see that.
Going forward, definitely "quarantine" your place for 3 weeks just to be safe. Don't bring your dogs out anywhere either. For me, I had stays already lined up when I discovered the dog was sick. I contacted rover support right away and afterwards I contacted each client that was going to be staying with me in the next 3 weeks to let them know what was going on. Most of them were extremely impressed with me being so up front about it, and were fine with their dog still staying here! I put myself as away so no new requests could come through, and opened back up once I had passed that 3 week mark with no one else coming down with it.
If it makes you feel better, you can request that any dog staying with you from now on needs to have the bordetella vaccine...but to be completely honest it does not work that well, lol. It's like trying to vaccinate for our people flu. It may help keep them from catching it, or it might help the symptoms be not as bad, or it could do nothing. They can even catch KC from the vaccine itself (That's how the dog I had visiting caught it), which is why if they don't get the vaccine 2-3 weeks before a stay it's usually better not to give it at all.
I've never had a dog catch KC twice, so after your dogs get better from this round I doubt they'll be at risk for catching it again unless they have a weak immune system.
Whew... sorry for the long winded answer! I hope that helps.
Edited to add: Sorry, I didn't see the date of this question before I answered. Hopefully this helps others in the future ^^;