You might go to the Trailer Life web site. They have quite an extensive list of trailer parks for Mexico. You have to hit the button on the bottom of the first page to find a city in Mexico. Here is their site:
http://www.tldirectory.com/index.cfm
I too have travelled through Nepal, and Afganistan as a photographer in the early 70's. Some of my photos there are on my web site -
www.richardvroom.ca. Look in the international section.
I too am looking possibly of taking my Airstream from Nova Scotia to Chapala, Mexico. I have many friends there.
Sincerely,
Richard