There are many 12 volt lighting fixtures to choose from at the RV stores.
As for routing the wires, if you want to hide I can think of two routes:
1) via the passenger side B post (I think that's what its called... hollow
channel that goes from behind the glove box up and over the passenger door)
and through the air channel above the slider door (on the Westy.... I don't
know if yours is a Westy or not.... Dang I wish people would remember to
post their vehicle year and model!). This is not easy it involves taking off
the headliner and the air channel and lots of fishing of wires.
2) Again, if its a westy you could bring power from behind the fridge,
rearward through the water tank and clothes cabinets and then over to the
passenger side following the speaker wires through the air-conditioning
cabinet (if you have air conditioning).

Let us know your year and model,
Good Luck,
Bill
90 Westy Syncro
-----Original Message-----
From: Elkavitch, Michael and Diana <elks@TOP.MONAD.NET>
To: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON).COM>
Date: Monday, April 05, 1999 4:01 PM
Subject: More light for rear interior

>Well, it is getting close to the time that Siegfried will carry us on
>vacation. I would like to add a reading light on the passenger side rear.
>Any thoughts on what/where to get one and the best way to install it? TIA
>        Mike
>