You definitely want a pure sine wave. I would suggest 1800~2000 watts. Keep in mind that most ratings on watts are peak.
Personally I went this route for my inverter
http://www.wholesalesolar.com/produc...m_ms_2812.html It is spliced in to the electrical line prior to the electrical panel. So when I turn the inverter on I have power to the entire coach. I don't have to run electrical cords. This also replaces my converter with a 4 stage charger.