I'm confused - you have a buddy pass? Doesn't that mean you're traveling with your fare paying buddy? In the program I'm in (USAirways) I
have to be on the same flight as my buddy. Might want to check that before you commit to a room.
If not, I would pick the oddest day/time that you can fly. In the last several years with all the airline consolidation most flights to the Caribbean that I've been on have been
completely full. Several even oversold - to the point where they were offering compensation even before the plane started boarding. Being Non-Revenue you wouldn't have a chance. We used to fly red-eye's to save money also, the last two I've been on were similarly full. One of the best times seems to be Sunday late afternoon now. Except you might run into some last minute travelers trying to get home to go to work on Mon. morning - my dive buddy is one...lol.
I don't think you can camp out overnight at the Bonaire airport on your return if you get bumped there. So you might want to have a backup plan. Wannadive has some fairly cheap accommodations on their website. One option:
http://www.divehutbonaire.com/?p=676
You might also look into flying into Curacao and paying for the flight over to Bonaire - it's relatively inexpensive. You can get to Curacao pretty late and still catch the last flight over to Bonaire - there's at least 2 after 6PM IIRC. Although it's contrary to my previous suggestion the best price is - Sat->Sat between Curacao and Bonaire - $54 R/T on Insel Air. Double that M-T, almost triple later in the week.
Bonaire typically runs on a Sat-Sat schedule as the red-eye from Houston arrives Sat. morning. So do the other United flights from the east coast. So the resorts/dive operations etc. are sort of set up for that. So maybe mid-week you might have a better chance of getting there.
Bonaire used to be a negative lift destination meaning that there were more available rooms than flights to fill them. IDK if that's still the case. If you're looking for budget accommodations - there's some options here:
http://www.infobonaire.com/hotelbudget.html Anything off the water will obviously be cheaper.
The last time we were in the ABC's in Summer - actually Curacao - there were vacancies everywhere. Our experience with Bonaire a few years earlier was similar. Just don't go around the 4th, the weeks of the Kiteboard tournament or the regatta weeks in Nov.?