Also, if you feel like you will fall off the wagon completely if you can't stick exactly to SBD, you can do calorie-counting or Weight Watchers from there but still trying whenever you can to stick to SBD principles! I did that for a while, just choosing foods that for the most part are SBD-friendly. That way you have some flexibility to diverge from SBD without it turning into a free-for-all off-plan extravaganza (which is what I tend to do
) ... I think the WW Points+ is very close to SBD now.
If you stick to the one rule of making sure you get 4.5 cups of veggies per day, it (in my experience) has been difficult to go terribly astray... My problem lies in making bad choices *instead* of the veggies because I'm too hungry or grumpy or whatever.
As long as you can wash your produce well, you will be fine for wonderful veggies. I agree, the fruit is amazing there. Maybe try to always have it with something else, like plain yogurt (I had that when I was there last but it was probably full-fat) or cottage cheese if that is available, or nuts.
ALSO - I just saw that you said you tend to eat one meal a day... look into the Intermittent Fasting thread! It consists of eating during a defined "window" of time, usually 5-8 hours, and nothing else except maybe a splash of milk in coffee during the other hours. It works for some people, especially those who don't like to eat in the morning anyway. You do have to make sure you get enough nutrients/calories in that window, though, so you would have to plan some additional food to your one meal, probably. I have experimented with this (using SBD foods, but obviously not the B-S-L-S-D-S schedule) and there is at least one other person on SBD who has mentioned it.
When I have lived abroad, I have had to hunt down the natural/health food stores to stock up on things like ww flour and brown rice. I haven't ever stayed in Mexico long enough to know about the stores there, but in other countries, I have been surprised to see things like Laughing Cow cheese and "fitness" bread in very unlikely small grocery markets. So you never know, but you will have to hunt around and/or journey away from where you are staying and/or bring what you can with you. I traveled with aseptic pack tofu and brown rice on my last trip! And I actually made tortillas and refried beans and salsa because I missed these things and it wasn't possible to find that in stores.
I would start by searching for stores in your area. Searching for vegetarian in Mexico will give you some natural/health food stores. For example, this list
Anyway, you will be fine because you are thinking ahead and you will have a plan in place before you go. Also - plan exercise. Don't know how easy it will be where you are (are you lucky enough to live near a beach or mountains with hiking trails?). For long trips, I travel with exercise bands, a yoga mat (thin; packs easily) and some DVDs (30-day Shred - but you would need weights - belly dancing, pilates )
Have fun! I am jealous!!