A truly prudent RVer is always looking for the far-sighted, thrifty, wise, frugal, vigilant, and wary thing to do. It sounds easy to do, but too many times something gets in the way.
I propose that a prudent Rver should have a Sun Oven; that is some device that uses the sun's energy to cook food.
I have measured the energy required to cook a pot of beans with a ham-hock in a slow cooker. It is just a few kilowatts of electricity. Or you can do it over a low propane flame for 7 hours. It is just a few cents worth of gas.
You do not save a whole lot of money by using a Sun Oven, but on that day when there is no electricity to be had or propane to burn, the sun can make the difference between chewing on dried beans and enjoying a plate of cooked beans.
And it is not just beans that you can cook with the sun. I have had BBQ and Teriyaki chicken breasts, beef stew, minestrone soup, baked fish, and pork chop stroganoff cooked with the sun, all in the last three weeks.
I agree that living in southern California helps by adding to the number of days I have sunrays with which to cook. But I have cooked using the sun when the wind was blowing 30 mph and the temperature was in the 40s and 50s. If you are so minded, you can cook with snow on the ground if there is a good sun you can shine into your oven.
A Sun Oven can also be a means to boil water for purification – a measure sometimes necessary in emergencies.
There are different kinds of Sun Ovens. I use the one from gogreensolar.com, but there are others that work equally well. The key is to get one and use it whenever you can. In time you may find it is the only thing keeping you alive.