I do have a not so small inverter generator in addition to my on board 5500 Onan. We did go for years without one but now after having had it, I'm happy to have it when we're boondocking and it is fantastic when we're at the kids desert cabin and power is $30,000 away or when I prune the trees and bushes that scratch the dickens out of my Winnie driving up to our home.
I'm not trying to put you down for asking a good question but there are a few really good sources of information online regarding RV electrical. Reading "The 12 volt side of life, Pts. 1 and 2" are among the best. The reason I suggest this is that the truly helpful answers you get will make more sense if you are familiar with the basics and the vernacular of the field. I've been in the electrical trade it seems forever and still there are idiosyncrasies that RVs have and I am still learning about RV electrical.
