The List is often long on theory, and sometimes long on practice.

My experience is as follows.

I have used my 86 straight stock Syncro to tow vans from all over with a tow
bar.  The longest was 3000 miles, towing an 85 Westy from LA to Minneapolis,
via Houston.  Cruising speeds were 50-60 mph on the level, much less uphill.
It was in January, so overheating wasn't an issue.  Trip gas mileage was 16
mpg overall, proving that speed, not weight, is the critical element.

The basic rules are to leave LOADS of following space, try not to have an
emergency manuever or braking situation (which could easily result in a
jacknife), and refuse to drive if the road is slippery.  The tow combination
seemed more stable in crosswinds than the Syncro alone.  My guess is that
the tail-on-a-kite (or feathers-on-the-rear-of-an-arrow) theory explains the
added stability.

It was not a relaxing drive as the towed van has a tendency to want to steer
itself over any imperfection in the road, and you know you really can't stop
fast if you the need arises.  However, it is well within the physical
capabilities of the Vanagon drivetrain.

Conclusion:  It can be done, with a modicum of safety, although towed
vehicle brakes would be a huge improvement.

Best bet:  Get a larger, more powerful and heavier tow vehicle and use a tow
dolly or 4 wheeled auto transporter.  It will be safer and more relaxing,
but, alas, generally considerably more expensive.

Budd Premack
86 Syncro, 88 Wolfsburg (+ others)
Land of Sky-Blue Waters
Minneapolis, MN