I wont be able to check on any of these till back in Florida but I have never had the front end apart . . and I have owned the bike since new, 40,000 miles on it without an issue.
Im sure its not the output shaft bearing. Water pump would be all the time not just under hard acceleration, same with oil pump. The only bearings up front are input shaft and counterbalancer. That leaves clutch, cam chain tensioners or something odd like fork tubes or intake manifold. Dealer said he has had the clutch make a squealing sound when it is going. Keep in mind I am a big boy, momma isnt exactly twiggy either and I have pulled a trailer for many of those highway miles. All power restrictions are off on the ECM and equipped with a darkside.
I'm betting on the clutch for now but am still open for suggestions . . I've got another long trip coming up in a couple of months (Florida to Maine) and need to figure this one out.