Can't help with boondocking but we're in Lo de Marcos for the winter at Cruz Maria RV park. Small, well maintained park w/ 21 sites. Can accommodate large rigs and on a great beach. Great quiet little Mexican seaside village that hasn't lost it's charm or identity. Here you are below the Sea of Cortez on the Pacific Ocean. Water temps are swimmable all winter.
The larger sites are usually reserved for seasonal visitors but worth checking. There are other parks in town that could probably accommodate you as well. We would definitely stay here again
1998 Newmar Dutch Star, 3126B Cat/ Freightliner
2003 Honda Element
" Don't let the same dog bite you twice "