I have an earlier version of the larger one here http://paulcbuff.com/vagabond.php
Works great, recharges from the car or the wall.
If you can get the car close, all you really need is the inverter.
Any given set of exposure settings, in any given lighting situation, will get very similar responses in A or D.
The difference is film simply not having instant review. That's not a required element.
Oh, and if anyone ever plans on using an inverter plugged into the car, make sure you get a pure sine wave inverter...a standard one can fry your flash.