Good for you. We have a good friend who travelled in Mexico in a motorhome as a single woman without a large dog for many years--into her 70s. She had to stop driving when her eyesight gave out.
We don't know Baja, but we know the mainland very well and wintered in Mexico without major issue until last year. I won't get into that here.
Here is a link to
our blog Don't dwell on last seasons problems. Go back and browse previous posts.
An absolute must is A Travelers Guide to Mexican Camping by Mike and Terri Church. Available at major book stores and Amazon. Here is a link.
http://www.rollinghomes.com/You should also get a good Mexican Road Atlas. Guia Roji's Por Lass Carretrras de Mexico is the best one. Also Garmin has a good Mexico map. SOME of their new ones (the RV one for example) include Mexico maps with the rest of the North America City Navigator map.
I think you might prefer the mainland west coast. The roads are a little wider it think and there are a lot more larger cities.
For the first few days there will be LOTS of driving. You can make Nogales to San Carlos in a day--a long one though.
San Carlos is a pleasant place, lots of Gringos too.:)
San Carlos to Mazatlan is really long--10 to 12 hours depending on your driving speed. There are a couple of options for overnight stops but they are an hour or so out out the way.
Mazatlan is a good place to settle for a while though not our cup of tea. Same goes for Puerto Vallarta, which we prefer for the climate--hotter.
Our first trip 13 or 14 years ago was to PV. We travelled in company of friends to Mazanlan then ventured on our own to PV.
For us, from the border to San Carlos was a White Knuckle drive, getting used to there being NO shoulders on the road and how close the oncoming trucks were. The lanes aren't always as wide as we are used to. On to Mazatlan we fared a little better and by the time we got to PV we felt quite comfortable.
I am sure that you will get lots more encouragement here. O course there will be a few idiots who will tell you how dangerous it is.
We envy you, perhaps will see you next season--we are not going this year because of an ill dog. After paying out all that money getting the new Jeep set up for towing. :(