I've been wanting to add some additional lights to the back of the
van to augment the somewhat feeble stock lights.  One of my concerns
is that when i have my bike on the back of the van, the lights are
partly blocked by it, making matters even worse.  I noticed this
light on sale the other day at harbor freight tools for $12.99:
http://www.harborfreightusa.com/usa/itemdisplay/displayItem.do?itemid=93263

My idea would be to put two of these in the back window at the upper
corners, glued to the inside of the glass.  They would be out of view
from inside, since they would be up in the area of the AC cabinet.  I
already have the electrical converter for trailer lights that makes
the 2 bulb light system work with the 3 bulb system of the
Vanagon.  So that would take care of that issue.  I went and looked
at it in the store, and they are bigger than I thought they would
be.  4 inches.  Later, I noticed some lights on trucks that I see on
my commute.  (I like trucks
lately:
http://www.flickr.com/photos/emaglott/sets/72157594574573264/ )  I
noticed what appeared to be this type of light fixture on some
trucks.  10 LEDs with a little magnifying lens for each.  5 on each
circuit.  Quite bright and that piercing LED light that really seems
to catch your attention.

This is a project just in the thinking phase, but here I toss it out
to the list for consideration...

Edward