You are an awesome dog parent, and you have tried so many things!
The only thing I thought of you haven't tried is to cover the crate with a dark sheet or towels.
That's my only suggestion. Luna cried in her crate when she was a pup until we covered it. Now, she doesn't make a peep, and we can leave it uncovered if we choose to. She's a year and a half now.
Worth a shot, chances are you already have something in your house you could try it out with.