re:  i was fortunate enough to get a Hella extra brake light
kit, years ago. it
consisted of TWO brake lights that went into the corners
(upper, lower, you
choose) of your rear window ...

I bet the Hella kit was marketed to emulate the cars of the
Paris-Dakar rally, who often use high-mounted rear lights to
combat effects of dust.  Not sure a Vanagon ever
participated in this rally.