Perhaps not Vanagon-specific, but many of us make improvements inside our
vans using wood for beauty and ease of working.   So here's a tip.

  If you are wanting a nice varnished finish, use a nice varnish.  Everyone
seems to  get caught in the "Varathane" trap.   It's what has sort of
become the norm, it's sold everywhere and people think it's pretty good,
must be, it's so often mentioned, etc etc.

 Well, it's actually pretty poor stuff to work with compared to a good
varnish.      Every good varnisher has a favorite, or a few brands that
he/she prefers.   I kinda like Interthane, but I can't get it right around
home.    Whatever Quality brand you choose, it's probably going to be
easier to work with and give you a better finish than the stuff you're
offered at Home Depot or Lowes....Varathane...  A  good varnish might be
just slightly more expensive but when you spend hours sanding something,
you don't want it junked-out in the final coat...