Crate training my foster pup

I have a ~6-7 month foster pup. He is excellent in the crate at night. Just sleeps right through. He even goes into and out of his crate throughout the day and sometimes chooses to lie down in there.

When we need to crate him in the evening though, when he isn't ready to go to bed but we can't be there in the room with him, he barks and barks and barks incessantly and will not settle down. We have worked to desensitize him to the crate itself, lots of positive reinforcement, and he doesn't fear it. He is also ok with being alone for short periods of time, no big anxiety. But combining them is just endless barking.

I don't know how to proceed with helping him be ok with crating when we cannot be around. Trying to wait him out to reward him when he is quiet takes a very long time and I think is making him too anxious. I'd love some advice.