--snip--
> But this summer I'm planning a trip up 395 along the east side of the
> Sierra Nevada mountains. That's desert country because the Sierra scrape
> water out of the air as it passes over them.
--snip--

Right- and since it is you should probably carry 50%-100% more water than
you think you'll need just to be approaching the safe side. If the Westy
tank holds 13 gallons I'd go ahead and fill it (probably somewhere after
Cajon pass, tho- from what part of sillyville are you coming that you'd go
that way instead of up the 14?)  I don't have a Westy and I probably carry
that weight in liquids on trips out of town anyway- you should have enough
coolant to fully replenish the system one time (which is almost 5 gallons
right there), plus 2X the human/animal requirement and so on if you're going
to be doing any extended desert driving.
If your cooling system is well-maintained and you don't overtax your engine
I don't really see how that stretch of road is that big of an issue outside
of a couple of specific areas.
Having said that, for camping I'd probably take both the water and the means
to 'make' more. I don't know about your Goldberg device tho... when we want
water we just carry it, the old fashioned way. Now you're probably gonna
call me a purist again.
Anyway, most people that come up here don't seem to understand what an
average 10% humidity or less can mean to the human body, and proximity to a
lake or stream doesn't really make any practical difference. One may need to
consciously make an effort to drink enough liquids to stay hydrated, and as
they say, if you're getting thirsty you've already let it go too far.
As for those little towns along the way, many people are surprised when the
locals want them to pay for water. It isn't the cheap/take it for granted
commodity in some of those places that it is elsewhere- in fact, when
California made it a law that filling stations had to provide water to
paying gas customers I know that several of those remote stations eventually
closed down because of the cost of compliance.
I can see wanting to trim weight as general procedure but I think I'd try to
do it out of optional items rather than out of necessities. Anyway 110
pounds is a pretty small amount- you could easily get that in variance in
passenger's body weights, for instance.

Cya,
Robert