My trip to Central America last year was my first gluten free venture out of the United States. In general, Guatemala is a great place to be gluten free, since the diet is heavy on corn and rice, rather than wheat flour (harina de trigo).
I lived at La Iguana Perdida, a wonderful hotel and backpackers hostel, for 6 weeks while volunteering and learning Spanish. The management and front-of-house staff are English-speaking travelers themselves. The wonderful women who cook and make the place sparkle are from Santa Cruz and speak Spanish. No worries if you do not speak Spanish, someone on the front-of-house staff can translate your dietary concerns to the kitchen and check on ingredients for you.
It was a wonderful experience, and they were able to accommodate my gluten free diet excellently. They offer menu items, with gluten free options, for breakfast and lunch throughout the day. For dinner, they offer a group 'family style' meal that you have an option of signing up for each day. While many of their dinners would include gluten, they were always able to provide me with a GF alternative.
I look forward to returning someday, hopefully soon!