The Traveling Vegetarian?

Since I am applying to lead an expedition this summer into the indigenous lands of Peru I have been thinking about the effects of being a strict vegetarian abroad. While I spent a semester in Chile I allowed myself to eat local seafood (a habit that I still practice here in Charleston) but still never touched any other meats. In many foriegn countries, Chile included, vegetarianism is considered somewhat strange and most of the time I would have tell my waitor that I was actually allergic to meat. If the chef did not think that I may break out in a rash or have my throat close up not eating meat just did not seem reasonable. Many items on a menu that I thought were definitly vegetarian (guacamole) would come with a little meaty surprise (ham bits) tucked into the dish. A few times I was invited to a new Chilean friend's home for lunch or dinner, only to have to sheepishly point out that vegetarians also do not eat chicken to a surprised host. Many times I would sit around the table with my host family as the devoured beef and pork filled empanadas and stared at my plate of lettuce and sliced egg as though I were simply foolish for not partaking in a food that they thought was clearly better. Best yet, I gained around 20 pounds due to the fact that I would try to fill up on bread and Coke if the only thing on the menu that I could eat was a small plate of shredded cabbage and tomato.
All of these situations could have been avoided if I had simply suspended my beliefs for a few months and delved into the local meat-based dishes that everyone else was eating.
This leaves me with a decision to make in regard to my upcoming trip to the indigenous communities of Peru. Is it okay to leave your vegetarian values behind in the United States because you will probably be more accepted where you are traveling? Because you can avoid awkward situations? Keep a few pounds off?