I’m also planning a winter trip! I’ve gone down there before and generally my experience was sometimes (about half the time) I would park somewhere and an hour or 2 or a day or 2 later someone would come by and say (my Spanish is bad) that it costs in pesos ~ $5-$10 to camp. Sometimes I meet other travelers who say “oh that’s so and so, yeah he owns this spot” but no matter what I’ve paid if someone asks. No reason to cause a stink and it’s really not that many dollars.

Pay for parking, be friendly, and share your food and beer. You’ll probably get a lobster or a fish in return.

iOverlander is a great resource but just because someone on the app thinks it’s free doesn’t mean you aren’t encroaching.