As someone who is driving a vehicle that has burned up once, I have a "plan
of
action" in place.  The first thing that you need to know, and the  thing that
keeps
me up at night trembling in terror, is that you may not KNOW that you have  a
fire for quite some time.  I keep an eye on my temp guage quite a bit,  as
well as
looking in my rear view and side mirrors.  My wife says I'm paranoid,  but I
prefer
the term cautious.
Ok. Lets say I see smoke billowing out the back.  I pull over as  quickly as
I can
and come to a stop (btw, since Vanagons aren't speed demons and I try to  baby
mine anyway, I am usually driving in the far right lane anyway).  I  run
around to
the sliding door and open it and pull my extinguisher from its location
behind the
battery box, trying to keep my cool so that I will remember to CLOSE THE
DOOR.
(The PO didn't do that and the sliding door panel burned to a crisp).   I
then take the
pin out of the extinguisher and direct the spray into the opening under the
rear
wheel well where you can get at the engine w/o opening the lid.   HOPEFULLY,
this
will at least cut the fire down enough so that I can then open the back
hatch and, using
the heavy gloves that I hope will be around somewhere, open the engine lid
to inspect/
suppress any continuing flames.
One final note.  I have heard that it really doesn't take so much fire
extinguisher "gunk"
to actually put out the flames, so I will try not to "unload" on it (if at
all possible) because
that crap gets everywhere and is a real pain in the a** to clean up  ;-)
BTDT.  I think the
whole process should only take about 1 minute ONCE I DISCOVER THE  FIRE.
Good luck to all, and I hope you never have to use this plan.
James in Houston, TX
87 Westy (The Phoenix)