So I ended up using the AT&T Passport plan as I have done in other countries. Unfortunately, in the heat of the moment, I didn't have the motivation to check out coverage at each dive site we visited, which was a major part of my original question. There was coverage in town, and I used Google Maps for navigation a couple of times, but that was all the roaming I did on the trip. Oh well. The waterproof canister worked well, and I stored the phone, money, credit cards and driver's license in it during dives, though wet money and cards would hardly have been a problem.
In keeping with the theme of having something resembling an emergency plan, I had entered into my phone's contacts list the numbers for police (the one mentioned in my original post to call if no one answers "911"), hospital, STINAPA, and the car rental agency.
Also in keeping with the theme, I made up some ziploc bags, each with a few assorted bandages and tape, as minimalist first aid kits. I figured that anything other than bleeding is something that doesn't NEED to be treated on site. If someone were to steal one of these "ziploc first aid kits" from the truck, it would be no big deal, as I had more (and if someone wants to steal cheap first aid supplies, they can have them). Maybe other divers have long been taking a few bandages with them in their trucks, but it just never occurred to me--the mindset of "leave nothing of value in the truck" was just so ingrained in me that I ruled out a first aid kit long ago.
So, now that I am a fifth-timer to Bonaire, I feel, like, all responsible and stuff
