Those conditions dictate patience. They're hearing the fish coming from a long way off.
I'd shadow them, and hope for any kind of weather (even wind, to whip up a chop, will help) to up the odds of success.
While you're out on the fringe, you might want to sprint out a bit, to give yourself some time to take a dip and find out where the thermal layer is. You could use that later, if conditions do not become optimal, to set up a sonar based vector analysis shot.
More than once, after tiring of waiting for "prime" conditions, I've used this approach. Set up a 60deg (or so) shot and wait under the thermal layer until just before the escort screen reaches my locaton (or, parallel to it). Timing it so that I can rise to a foot over max firing depth (based on the boat you're on) just before my first target is ripe.
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