I don't want to seem argumentative, but just another note on venting
the battery compartment:

At 11:23 AM 8/9/2011, Rocket J Squirrel wrote:
>... my aux battery, a honking but 130 A/h Trojan deep cycle, which
>lives under the bench seat. That's hardly an airtight compartment.
>Any hydrogen that bubbles out vents right out of the seat ... But
>under the sink ... the hydrogen leaking upward would pass right next
>to sources of ignition ... It might be dangerous. You go first.

The kitchen cabinet has a long vent at the top, extending the whole
width of the cabinet just under the window.  And the shelves and
dividers inside are anything but air-tight: There are big gaps everywhere.

Yes, there are ignition sources in there.  (I have a big ignition
source from Propex under my rear seat, too, as it happens.)

But to present a hazard, any hydrogen vented from the battery would
have to collect to create a combustible mixture.  It's hard to
imagine that happening in such an open cabinet.

So I'm comfortable going first.  (Or copying GoWesty's installations,
which precede mine.)  If I don't explode in a year or two, I think we're safe!

(Writing this led me to the Wikipedia article on "Flammability
Limit," which is kind of interesting.  Hydrogen, it says, is
flammable at 4% mixture with air, and explosive at 75%, if I understand.)