the wife and i plan on taking a camping trip in few weeks, we are going to be camping on the water at a primitive tent site on a large lake and i'll be able to land my boat right on shore at the camp site....i want to get an DC to AC inverter to charge my boat batteries from my truck in the evenings ......iv seen them from 100 watts up to 800 and more.......not sure what i need, any suggestions?......battery charging is all i plan to do with it (im not even going to tell the wife what it is until we get up there so she dont get any ideasThumbs Up)