http://ioverlander.com/
We are aware of the I Overlander website and have tried to use it. Just looked and no indication of any campground of any kind anywhere near Oaxaca. Other RV opportunities we are aware of in Mexico do not show up on this website. It can be a useful site but not as good as either Church or Bell - using the Church book and their updates very useful as are the Bell's notes. We use them all and keep info found on all sources we can find. I Overlander seems to be making progress but not there yet. Not strictly an RV website.