<Anything which traps water against the panels will end up causing rust.>
<this includes plastic-wrapped insulation and any naked fiberglass pads too.>

Yes, if the metal underneath isn't sealed from moisture, but in my case it
is totally covered with a completely water proof coating.  Also if the
space where the insulation is is sealed to circulation with the outside air
there is no watervapor to condense out in the first place.  All the areas
with insulation in my bus are sealed with plastic to form closed chambers
so that no watervapor can intrude.  They also are in areas where water
can't flow in from some other source without some odd occurance like
driving the van into a creek.  Even if there was room in the front doors
for some insulation I would't put it there due to the water that flows
through that cavity.   Likewise putting alot of padding on the floor
invites trouble if it isn't sealled in some other way, or no one gets in
with wet shoes or spills sodas.  I did think about the water issue before I
did this and did alot of research.

Thanks,
Dave K.