Has anybody done this in a sailboat? I'm wondering things like whether
public sighting reports are available, probability of seeing anything, etc.

It's not only doable, but it's easier to approach a pod under sail
without an engine. Went out on Stellwagen in late spring, dropped the
jib and had a great hour tacking among breaching whales. There were a
handful of tour boats in the area that kept a quarter mile off or
maybe the whales kept away from the stinkpots.