Just use a power inverter with a 110 outlet on it and charge away out of the car. You will find a power inverter more than desirable anyway.
Here's a link to what I am talking about regarding an inverter ...
Enjoy your trip!!
Buy the camera that suits you best. I would recommend either a Super Zoom like the Canon S2 or if you aren't going that large, I would recommend waterproof like the Pentax Optio W10 - nice for lots of trips, even to the beach!
Canon S2 w Raynox DCR1540PRO 1.54X Teleconverter
Hoya UV, Hoya Polarizer on Lensmate Attachments
Tamrac 5683 with Tamrac SAS Med Lens Case