I've had good luck with a marine deep-cycle battery. I've run a 12 inch box fan using a small inverter all night and had plenty of power to get her started in the morning. The alternator is more than up to the task. If all else fails I carry a jump starter. Even a small one will bring the little four to life. So far I've never used it.
In the summer I use a old small boat trick to cool the cargo area off. I fill a 64 quart with dry ice, easy to find in FL, and place the fan on a grate just above the ice. Amazingly effective in all but the hottest weather.
All the best.
