Making a fool of myself here, but hopefully it helps someone else in the future if they find this thread. Per the dealership, their senior master tech was unable to identify any issues with the driveline, and pointed to "heavy cupping" of the OEM KO2s as the cause. Prior to this, I had the tires RF balanced as soon as I felt the vibration as a means to eliminate them as a possible source (it didn't help), and did not even know that cupping was a thing. Based on a few other threads, this doesn't seem like an uncommon issue, and after dropping the PSI from 38 to 35, I've definitely noticed a reduction in the vibration at all speeds.