Another possible solution would be to check with Chapala.com Webboard (Powered by Invision Power Board) for house sitting. This board is by far the most active in the Lake Chapala area. You will have to dig through some of the craziness, but there are a few diamonds in the mud.

House sitting/watching is becoming very popular as folks going away for a month, two or more, like the idea of someone keeping an eye on things. Besides, it costs nothing to ask. There are folks who move from house to house year round. Heck, even a place available for one month saves one months rent.
Verde-Va