A good introduction into figuring out what you need vs. want and a primer on RV electrical http://www.jackdanmayer.com/rv_electrical_and_solar.htm
When we are not on "shore power" all of our needs a re supplied by a 185W high voltage solar panel but our 'needs' are supplied differently i.e. coffee is made using a french press, water is heated using propane. A 300W inverter supplies the TV/DVD, laptop etc.
Boondocking requires a different set of tools and thinking unless you can not live with out them in which case you have a noisy smelly generator.