This past fall I did a similar thing, flew to Reno and drove my 'new'
Vanagon Carat to Connecticut.  I didn't have the luxury of bringing a lot of
things (and if it had died on I-80 in the wilds of Wyoming, I doubt I'd been
able to get it fixed.  That being said, my advise:

1 - Make sure you've had a good pre-buy inspection from a reputable
mechanic.  I did this with mine, and discovered a bad waterpump (which was
only 6 months old).  Glad it was replaced before I got to NV.

2 - Bring your Bentley.  Even if you have a mechanic, odds are he doesn't
have the book for a Vanagon!  I packed mine, luckily didn't need it.

3 - Bring cash and plastic!

Seriously,  If you've inspected before going, you shouldn't have a problem.
I made sure I checked all fluids on every stop for gas (obvious thing to do
with a new car that you're not familiar with), tracked the gas mileage and
the inflation of the tires.

Good Luck, and post pictures.  Also, don't forget to enjoy the ride.  (Lucky
dog, a Westy,  All I had was a weekender back seat to sleep in....)