Kurt, we just used our LBO cards last week on our return. No float plan is required, just phone in, give them our LBO numbers and get an entry/clearance number, took less than 10 minutes although you do need your customs decal to use your LBO cards. I am like you, I am not filing a float plan with the Govt. One other nice advantage of the LBO cards is that we had a few other people with us on our return last week and I got there clearance on the same entry number. They still had to go to the CBP in person, but it was much quicker for me using my LBO card and just adding there names and PP numbers as passengers.
The CBP guys at the cruise ship terminal in Ft Lauderdale are very friendly and helpful, the guy even made a joke. I wanted to clarrify where my brother should clear in person and asked the CBP if he was physically at the cruise ship terminal and he said "no, I am in India". Ha Ha pretty funny coming from a CBP agent. You really should entertain changing your travel dates to June if at all possible, we have completed nine Bahamas trips during June and July and of the 18 crossings, only one time did we change our return date and that was by one day, and it really wasnt necessary.