We're doing a destination wedding on a cruise on 10/15. All money is due from each guest by 8/15. We've already sent Save the Dates, and anybody that's going will have started making payment arrangements w/the cruise line well before August. Do we still need to send out formal invitaions? It just seems so odd to send an invite out for an October wedding in June, especially when word of mouth will have told us who's coming and who's not. Thoughts?