Pat, A good battery is the place to start, imho.  And enough has been said about that and you will get lots of great info here once you determine if you need to do some mods.
Once you have that powering all the extras you can look at how to ration it out, and add to it. Driving of course, however a small solar panel can go a long way if you're light on using the power. The PO of my westy was able to go at least 4 days in the Mojave with water becoming short before electricity. 

Here's a shot of the panel, just by the westfalia logo.
http://picasaweb.google.com/pkraiker/MyWesty#5489868349070009842

Regards, Peter Kraiker
kraikerphoto.com / studiofstop.com
Toronto, ON, Canada
'82 L Westfalia 1.9 TD 5 Spd (Babe)
'05 Jetta Wagon 1.9 TDI 5 Spd (Blue)

On 2010-11-11, at 3:35 PM, Pat Sloan wrote:

> . Mostly I will be camping in one place for 3 or 4 days max. I will not be
> winter camping or heading for the arctic, and plan to make-do with a good
> down quilt if surprised occasionally by high-altitude or global warming
> blizzards (I've lived at 40-below and know how to stay safe). My cooking
> will be with a Coleman stove and food storage in an icebox/electric cooler.
> I will probably bring along some kind of portable heater, but don't intend
> to run it continuously. A lot of times I will be in campgrounds, but I
> definitely want to be off-grid capable, in case of necessity or completely
> irresistible location. I mostly want to be able to charge up my laptop,
> camera and phone and briefly use the inside lights at night. So it sounds
> like a permanently installed large solar array would be overkill for my
> purposes at this time, but could always be installed later if priorities
> change.