Someone posted a question about where to locate a 12V power source in
the passenger area for adding some additional lighting.

Well, if you have an '86 - '91 Westfalia, above the sliding door is an
air duct for bringing fresh air into the cabin. Inside this air duct is
some heavy gauge wiring wrapped in black plastic.

I can only surmise that this wiring is for the AC evaporator fan and
thermostat, which are in the back AC cabinet. I don't know if this is
switched 12V DC or whether it's hot all the time (which you would want
for lighting). But, even if this wiring isn't appropriate to use, you
could still run some dedicated wiring through the duct, as this seems to
be an ideal place to mount fluorescent or incandescent lighting. I plan
to explore this option. The duct comes apart, so running the wiring may
be easy.

Another place to add a light, in my opinion, is right above the engine
compartment. This would double as both a luggage compartment courtesy
light and an aid to viewing the engine at night, should one need to. It
would be a simple matter to add a fluorescent light to the ceiling
panel, right below the AC evaporator.

My '82 Adventurewagen has lighting like this in the back.

Dan