I think it is possible to seal the panels. WHen I did my van I used
the bubble wrap as a vapour barrier over my insulation, glued the
seams with vapour barrier caulk, and then went over all the seams (and
many holes) with industrial grade 2" packing tape with a tape gun. I
feel confident that in a water crises I could use the interior voids
as emergency water tanks.
.  Also, I did not bother with vapour barrier, way too
> > hard
> > to do a good job in the westy...too many factory holes
> > everywhere...and
> > I like the holes and gaps to allow any moisture that does
> > inevitably get
> > in to get out fast in.

The vapour barrier is on the inside because it will almost always be
the warmest and most humid. Not to mention that if the van is in
proper shape the exterior walls/windows will be a perfect vapour
barrier.
>
> The vapor barrier is a critical element.  Vapor migrates from warm to
> cold, so if you stop it from traveling to where the dew point is,
> somewhere in your insulation, w/ the vapor barrier, it does not form
> at all in your insulation.  Now if it is warmer on the outside than
> the inside, then the flow reverses direction & you trap it in the
> insulation.  But generally, vapor barriers are always put on the warm
> or inside of the insulation. The best way to do this is like the
> current auto mfrs' do, glue a continuous vapor barrier over the
> entire wall/ceiling/floor w/ as few holes as possible, & then place
> your finish panels over it. A reflective foil works even better than
> plastic sheathing, as it reflects radiant heat like mentioned above.
>
> >
> > BTW, nothing beats a good sleeping bag and another warm body to keep
> > warm while camping ;o)
>
> I use a 0-20 degree F bag all year, just opened or spread out
> differently depending on air temp, SO next to moi or not.
>
>
>
> Tom B.-can you say low emissivity (low E) barrier?
>