Try going back under to your sending = unit and pulling it out.  When it is out take the rod and bend it = DOWN.  How much, it's hard to say.  But with a little trial = and error you can make your empty mark were ever you want it.  I = have not done this with the Vanagon but my 82 Chevy pick-up had the same = problem and it worked great, I set it up to the Empty line on the gage = had 2-3 gal. left.
Looking through my Bently it looks like this would = work just as well.    
Ronald P. Mc Donald =    mickeyd@iswnet.com