I would say unless you are sending your resumes to companies here in the US you are probably wasting alot of postage. In Mexico, as much as things have improved re: employment we still have the "brother in law systen in place", i.e, it's who you know. I stick to my earlier advice about going down and doing it in person. Why would they take a risk of hiring someone they cannot even see when there are 10 in front of them ready to go? Save $10,000 and go check it out. If you find something...great. If not, you had a great 6 month vacation! I respect that you are a TA. I love 'em! But you will still have to get to Cancun and find your place.

Good Luck!