I disagree with the non-rigid theory.
If the Vanagon had a piece of 4" water pipe filled with concrete bolted
to the rear or front of it and got smacked, or smacked  one of the new
world collapsable toilets that are motoring about today, I guarantee
that the Chevy Corsica, Ford Focus, or whatever junk that has just
messed with you would lose, and you would be just dusting off your
bumper, and moseying down the road.
The Vanagon isn't made out of tissue paper like the late model garbage,
and a solid bumper(s) would stop a lot of geeks, attempting to damage
your baby.

  ______________
 |[  ] [  ] [ ]\
 |    |    |    |
||-(())----(())-|

Terry 85 GL