Grant,
These engines in their original application have a thermal switch near the
intake manifold that activates the fan when under-hood temps become excessive
contributing to "hot soak" problems as you have described.  Since in the
Vanagon engine compartment there is no fan, it may be that a fan could be
installed to cool the engine compartment. I also have a 2.0 Golf ll engine,
and I have thought of adding the fan since it was originally designed to have
one.
  I am not sure if "hot soak " is your problem, but a fan could cool the
relays down if that is the problem.  The ECU doesn't use a lot of amperage,
so there should be any significant voltage drop at hat distance.  With a
harness this long, you could place the ECU under the dash and with Darrel
Boehler's Digitool attached and permanently in the dash, you could know the
state of your engine sensors while you drive.  Wouldn't that be cool?

Robert Keezer
1982 Westfalia
Seattle