I think you would like the GoWesty kit:  http://www.gowesty.com/ec_view_details.php?id=2418&category_id=&category_parent_id=Since mine is a non-Westy, I used the other kit they offer.  Similar.  Had no problems with the install and no problems since.  Add a Walmart group 41 battery for $100 and you are all set.
The instructions they provided when I did mine were not super clear, but that was 7 years ago and I think they've improved the instructions since then.  Even a YouTube video to watch on their website.
RichSan Diego
      From: Eric Caron <ecaron1@COMCAST.NET>
 To: vanagon@GERRY.VANAGON.COM 
 Sent: Friday, October 9, 2015 11:30 AM
 Subject: Recommendations for Aux battery hardware
   
Hi Listers,

        I’d like to add a Aux battery to my Westfalia.  It did not come with one.  the spot behind the driver’s seat is currently a storage area for my battery tender and other odds and ends.

So,  Which ket would folks recommend?  Which vender?  I’ll need good directions as I’ll have to find a assistant to do the install with me. Cal usual VW shops here tell me they will not do any camper equipment work.

So, Which kit from which fender will install fairly easily? 
I basically want to run the water pump, refrigerator fan, rear light and radio. a 12 volt adaptor for items would be a plus.

I’ll be watching the other thread about batteries for tips there but I’ll probably just move my current starting battery to that position then look for a new starting battery.

  
No current plans for solar additions but you never know what I might do years down the road.

Recommendations are greatly appreciated.

Eric Caron 
85 GL Auto Westfalia