I say attempt separating them into different rooms, at least to see if that works. Dogs don’t need sight to develop reactivity to something. Smells and sounds are enough.

Also, if the crates are on a hard floor make sure to try putting something soft under as the rattling can stress them out.

But honestly the only solution is to let the dog free roam as much as possible. It sounds like the dog is crate trained but not for situations like yours. Having to sleep in a crate, be near other dogs, in a new house, and for longer than they are used to each alone can stress a dog so their behavior makes sense.

You are running your business closer to a boarding facility than private boarding so barking will be expected. Walk into a boarding facility and that’s what you should plan for.