Exactly what I was thinking and why I ordered a set of those windows earlier this week.   These later model vents? Do they vent too much for the cold nights?  I beleive it is one way venting.  
 > Date: Wed, 2 May 2012 13:48:07 -0700
> From: syncro@GMAIL.COM
> Subject: Re: Cabin Air Flow
> To: vanagon@GERRY.VANAGON.COM
> 
> Didn't the late model rear side windows accomplish this?
> 
> http://images.cars.com/phototab/DMI/103836/004289.jpg
> 
> http://www.van-cafe.com/shop/images/USED.REARWINDOWS.jpg
> 
> Or install rear sliding windows like the SA vans.
> 
> 
> BenT
> sent from my electronic leash
> 
> On May 2, 2012, at 11:46 AM, Steven Shelton <shelton4@GMAIL.COM> wrote:
> 
> > A few years ago I bought a rear hatch lock extension bar.  It came in a bag
> > with text in German so I didn't know that it wasn't recommended for use
> > when driving (making it of very limited usefulness if you have the rear
> > screen).  With the extension bar in place while driving with the windows
> > open, the air flow through the van was smooth and laminar, far superior to
> > the buffeting we get normally. It made driving in in a Georgia summer
> > without AC bearable.  I confess that I have occasionally used it while
> > driving since discovering that it is not recommended, but exhaust gases
> > sometimes leak in.  I would like to come up with a way to achieve this air
> > flow without the complication of carbon monoxide poisoning.   Has anyone
> > come up with a modification that did this?