Interesting thread. Assuming Texasfungal is indeed a gal, I'd say you'll have no problem whatsoever wearing thong swimsuits, although you may very well be the only one. For guys I'd say it's a different story; you'll need a pretty thick skin if you venture away from the topless deck in a thong.
One thing to consider, if you start the party, others may very well join you.
I just noticed that Texasfungal is already on her cruise. Let us know how it went when you get back!