Ron,

I'd recommend NOT driving in Mexico at night.  The following occurred in
1984 in the Yucutan area of SE Mexico, and times may have changed, but...

Driving at night from Villahermosa to Palenque in a rented VW bug.  The
roads usually have no shoulders at all, frequently dropping 3 to 10 ft
straight down from the pavement edge to a very wet mire.  The other cars on
the road are nearly always VERY used cars, held together by God knows what.
 The people are very poor and if they can afford to buy and operate a car
at all, it's probably something rescued from a USA junkyard.  Many people
walk on the road at night when it's cooler, and as I said, there's often no
shoulder at all.  Most Mexican drivers seem to think (in that time and
place) that turning on their lights is either 1) impossible, because the
car's such a junker that they don't work, 2) bad luck, as they attract evil
spirits, 3) inadvisable, as they are believed to wear out the battery more
quickly, or 4) a real man doesn't need them so whoever turns them on first
proves themselves to be lacking in machismo.  The above will offend only
the inexperienced

With no road shoulder, inadequate signage, lines or other road markings,
occasional poorly- or unmarked road repairs, pedestrians and (I almost
forgot) bicyclists who have no lights, and rattletrap clunkers with their
lights off zooming up out of the pitch darkness, you soon learn why there
are innumerable little white crosses along both sides of the road.

Stick to the daylight when you can see what's going on.
We didn't camp, but stayed in very inexpensive motels and hotels which
abounded.
Tijuana is full of auto repair, painting, etc shops.  I don't know how you
know which ones are good.  Let the buyer beware...

Chuck Almdale