Part Three: Entitlements and Studies.
One of the major misconceptions foreigners have regarding Mexico is a general belief that Mexico is "backwards" and "anything goes"! I have heard horror stories about built "back-of-the napkin designs without permits suffering huge fines and back taxes. This belief that Mexico is the wild west, in this respect, is erroneous, and if you follow this path, you may end up in trouble with fines, or orders from the authorities to tear down.
NO, as it turns out, Mexico has very sophistocated laws, procedures on the Muncipal, State and Federal levels. AND YES, they do require permits to construct anything over 20m2 (215sf) in most municipalities; and some require permits for walls, as well. (Here, municipality - "municipio", in Spanish, refers to "county", more so than a "city" jurisdiction. For example: La Paz is a municipality, Los Cabos is a municipality, etc. There are 5 municipalities in Baja California Sur: Los Cabos to the extreme south, La Paz, Comandu, Loreto and Mulege, to the north. Each has its own "building code" twist, much the same as Los Angeles County slightly differs from San Bernadino County in California, even though they are next door to each other. Each municipio has its own building department, planning department, "city council", and governing bodies.)