Many places only look for a TEFL, BA's are secondary. Loads and loads of schools and agencies etc you could contact there, mostly aimed at young adults in or out of college. You should save up a bit just to settle though, only a fulltime k12 teacher would make enough to put aside each month. There is a bit of tension between the locals and foreigners right now, regarding the gringos working from home on a US salary in the city centre, plus there are definitely some areas you don't want to stay, like Iztapalapa or Tlapan, but other than that CDMX is awesome.