Right off the top of my head, I'd say keep your aeration schedule as it is, or run it 24/7.
Are there other fish in the pond? Do you have extensive submergent vegetation? Either of these two could increase the oxygen demand during the night.
I've had your numbers and sizes of trout in my only slightly smaller pond along with hundreds of LMB, sunfishes, YP, grass carp without any shortage of oxygen whatsoever, with similar water temps. And this is without aeration during our warmer months. We do have a trickle of fresh water running into the pond.
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