You haven't tried enough.

  Well, nice discussion but it doesn't alter the way 2wd Vanagons normally
behave.   They just are not as good, traction-wise, as many other
vehicles.. On a scale of 1 to 10 I would rate mine about a 3..maybe a two.
  I had a long bed 2wd ford pickup that was awful in snow...I'd give that a
3 maybe 4..... Oh, I've made lots of improvements trying to make mine go
better but it still gets stuck without much effort, if you are not really
careful about how you ask it to move....  If I park on any kind of slick or
soft surface that has any slope...I better park headed downhill, or I am
stuck.   If I stop in sand...stuck.   If I have the front wheels turned in
sand and try to move...stuck.   If it snows while I am away from my
house....I am stuck at the bottom of my driveway...

  This is with brand new Nokian Hakkapellita mud and snows on the rear, the
suspension reworked and the van corner balanced and many years of snow and
sand driving experience...They just plain don't work that well..You *can*
drive around this crummy traction, most of the time, but I think it is one
of the few things my Vanagon does badly....

   Yes, a limited slip diff would be a huge improvement...Or better yet, a
full locker for when you need it...

   I think it is partly due to the rear suspension not being particularly
supple or having very much travel...It doesn't take much to get a wheel
completely off the ground at the rear...there is little "droop" in the
Vanagon...Droop being the amount a suspension will hang down when the
vehicle is lifted....

   When it begins to snow and sleet around here I have to load at least a
few hundred lbs onto the rear deck lid to keep driving my vanagon without
being constantly stuck...that's not very convenient nor safe and it is a
real pain when you need to access the engine..