I'll second Malcolm's comments about false economy in
getting the van ready and add:

Head out with excellent tires--all five.  There is
too much talk on the list about tires and trying to
get away cheap.

I just drove 3800 miles, 1500 of them in Baja California.
     http://coyote.colorado.edu/~jones/Baja
I had nearly new Agilis 51s (185R14).  In Baja, there
is no shoulder; in fact, usually a dropoff just past
the white line of 6-20 inches.  The lanes are narrow
and there is a lot of semi traffic.  There is no
room for error.  Plus sometimes you are dancing the
whole road trying to avoid more potholes than you hit.

It occurred to me what a disaster a blowout could be
and what a pain a flat would be.  If you were stranded
100+ miles from the nearest town because you had
bought cheap tires, you'd give a lot to turn the clock
back and buy better!

                                Richard A. Jones
                                Boulder, Colorado
                                '81 Vanagon   Mr Bus
                                '87 Syncro Westy   El Jefe