Brian,
You can see how I installed my auxiliary Optima under the driver's seat.
A primary battery would be the same, just wired different.   Check it out
at:
http://home.earthlink.net/~matsuwesty/page41.html
If you have any questions you can e-mail me.
Matt

>Subject: Calling all OPTIMA BATTERY USERS!
>To: vanagon@GERRY.VANAGON.COM
>
>I posted this question a few weeks ago, but didn't
>really get the replies I was hoping for.
>In the past I have seen a number of discussions about
>how great the Optima batteries are. Now I want to put
>a Red Top model in my van and can't seem to get any
>help. I want to put it under the Passenger seat as my
>primary and only battery. The battery dealer, who is
>also a shop that works on vanagons, says it won't
>fit-it is to tall and will cause a fire. I asked if it
>could be layed on it side. They said they would sell
>me the battery, but installing it is up to me.
> I measured a red top and the compartment under the
>seat and it seems like this could be the solution,
>(laying it on its side).
>I am open to suggestions to other Optima models as my
>primary/starting battery, If there is indeed an Optima
>that can be used for this application.(If there are no
>Optima batteries that work for this application, I
>would listen to suggestions regarding other high
>quality options).
>Please reply with any advice regarding this subject.
>Please do not reply if you have found a groovy way to
>wire your secondary battery and strap it to the roof,
>or any other, or any other subjects which do not
>pertain to my query.
>Thanks in advance,
>Brian Butler