I have given this some thought as well.
It seems to me if you got connected with a tank builder or fab shop you
could have an aluminum tank
welded up that would be very simple for the section right under the sliding
door .

There is a large cavity there that has strong frame rails on both sides you
could attach the tank to.
You can decide how low you want it to go, the westy propane tank height
would be a good benchmark.

I would connect and vent it directly into the main tank and install a small
faucet electric fuel pump and "pump in" to the extra tank
from the main tank. Yes, you might have to make two fill ups to fill both
tanks but how often do you need all of the fuel?.
I would also pump back into the main tank from the aux. Again slower not as
convenient but it eliminates most of the headaches
of trying to design a totally separate system. if your main tank got down to
almost E you could just flip the switch even while underway and
begin to replenish the main tank.

If you  are not running the propane tank you could install one on each side.

Doug

----- Original Message -----
From: "Brien K Dews" <briendews@CHARTER.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, September 24, 2004 7:13 PM
Subject: Longer range gas tank?

> With all this gas tank talk...is there a larger after market gas tank for
> the Vanagon? Looking to increase my distance between fillups on longer
> trips.
> Thanks,
>
> Brien K Dews CC
> www.busesbythebeach.com
> (84' Westy)
> www.allgoodtime.com
> 616-863-8463