Hi Esther, I just discovered your RR and read it all. I have been planning my first moto tour of Baja and your adventure has bouyed my confidence.
There are a couple things that I want to tell you about. You probably already know about them, but I have not seen any reference, so, in the off chance you don't, here they are: The first is www.couchsurfing.org
It's a site that lists thousands of people with couches all over the world where you can stay for free. In your case, I'll bet that at the least, you could find someone with a back yard who would let you set up your tent. The second is www.airbnb.com
. Pretty much the same thing only the accommodations range from tree houses to villas - but they aren't free. The owner sets the price - often less than a campground. Again, you could negotiate for tent space in the yard, probably very cheaply. Most accept last minute reservations.
I hope you find these useful - and that if you are ever back on the west coast (Grass Valley, CA) you will take advantage of our couch (or back yard). Rick