Thanks Tom, Good advice and great coverage of your trip. I've run into many of the same issues and a few more.
Once in Placencia Belize we found via email a double Tofino to take on a private trip to the outer reef. If Ed Gillet would take one to HI, It should do the job for us.
The rental was $25/day and they had PFDs and paddles -no problem. On arriving, the Tofino had a big gash in the side-hurricane, mon-no problem. Fortunately, I had brought glass cloth, which can be hard to find. They have mainly very coarse glass mat for repairing pangas, but resin is readily available. After fixing the fiberglass, we started looking at the gear. Fortunately we had brought our own skirts, as the the nylon ones had no coating left, and leaked like crazy. The rudder cable was sketchy, but I did not need the spare I brought.
Then there were the PFDs, old Extrasport flip-up models. They looked a bit faded, and when we tried them on; the fabric split as they were zipped up.
Ok, some duct tape and an extra strap about the middle. Some low-cut PFDs would have been more comfortable.
After getting over a few hurdles like this we had a great trip to the outer reef in the double.
The point is, unless you are signing on for a well equipped commercial trip, expect a few glitches, and bring backup for what you are concerned about.
Solving problems and getting a trip done are part of the adventure.
Belize is an English speaking country-but most places in Latin America are Spanish Speaking-especially out in the boonies- which is probably where you want to go. If you are on your own-the most important thing you can bring is Language skills. After over 3000 nautical miles of paddling in the Sea of Cortez, I can't count the times that Spanish has help to add everything from safety, to food and water to hospitality on those trips. For example, A Mexican Marine capitan told me to avoid a beach near Punta Machudo because it was being watched for drug transfers.
Sometimes, valued trade goods or gifts are worth more than money in remote areas. On that Belize trip, An old guy living on a remote caye was so thrilled with a gift of some steel fishing leaders that he practically adopted us. Most local fishermen start their day well before dawn, or they may fish at night. An LED headlight might be especially appreciated.
Another problem can be bringing stoves and fuel when flying. I have disassembled my Optimus Nova and scattered the parts around baggage. The fuel bottle was washed of fumes and marked as a cooking oil bottle. Fuel is easy to find when you arrive in most places with the multi-fuel stoves, though white gas may not be available. Mexican Magna sin plom car gas works ok, but it smokes a little.