I didn't read the "thread" except for the subject so maybe this has been
mentioned...

   My Vanagon hasn't had problems with broken headlamps but if it did I
would do what I did on one of my dirtbikes, a KTM that saw lots of rocks
thrown up by other bikes ahead of me on fire roads and down in Baja.   It
had a flat lens, like my E-code lights in the van, so this would work on
the van also.   I had some 1/8" Lexan left over from a boat I was working
on so I cut a piece to cover the headlamp.   You can easily work Lexan with
home shop tools. You can cut it with a jig saw and smooth it with a
sander....I have a band saw and a router I rounded over the edges with...
I used some of those industrial strength stick-on velcro 'dots' to hold the
lexan lens shield onto the outside of the headlamp...Removable for cleaning
and  it never came off during riding or crashes.   That thickness of Lexan
is supposed to be able to withstand a 22 long rifle bullet fired at it....I
know it repelled the "roost" on some pretty wild motor excursions.   You
could probably use 'smoke' Lexan if you wanted the 'blacked-out' custom
look....The lens cover on my moto was smoke and I couldn't tell any
difference in illumination  with it on or off the bike.  Lexan is neat
stuff that I find many uses for in my van and boats.