I used some silver bubble wrap type insulation I found at Home Depot.
Works great and is easy to cut to size and install.  I took some out
this winter and discovered a little moisture at the bottom of one.  I
think what I will do is cut the bottom part of the insulation in notches
to allow any moisture to evaporate...kind of like weep holes.  While
your at it make sure you put some rust proofing oil in all the nooks and
crannies.  I use Krown or Rust Check and it works great at creeping into
the seems that most Vanagons have problems with.

Pascal 
84Westy

"I am pulling all my fiberglass insulation out of my panels because I am
noticing they are holding moisture.  What alternatives to fiberglass can
I
use in the panels in my syncro westy"