I'm going, first time in a Vanagon (5th time overall).  Include me on
the private tips list if one develops!

Regarding the alkali dust, all my friends have told me "it will
destroy your bicycle".  Well, I've taken my (nice/expensive) mountain
bike every year, and when brought it home I've cleaned and oiled it
and it's been just fine.  My friends have purchased $50 specials at
toys-r-us and they have indeed rusted out.  I think the main problem
is that cheap steel is, well, cheap steel, and a $50 bike will fall
apart just sitting in your livingroom.

My advice : when you get home, clean and oil anything that you would
normally clean and oil, but otherwise don't stress about it.

Oh, and if you were in a dust storm on the drive in/out maybe change
your air filter, but it is possible to get in and out without sucking
much dust if you drive slowly.