I got rave reviews for this crock pot recipe yesterday. Can't get much easier than a crock pot?
http://www.yummly.com/recipe/Slow-Cooker-Recipe-for-Creamy-Tortellini_-Spinach-and-Chicken-Soup-793674
This recipe, "Chili For A Crowd", serves 40 people. Make it for your family at home & freeze the remainder for an RV adventure later. The list of ingredients is long but it is more of an assembly job than cooking, really.
http://eatboutique.com/2012/02/01/the-silver-palates-chili-for-a-crowd/
My other ideas would require some equipment & wouldn't necssarily be easy but I've used these ideas to feed a "crowd": Seafood boil, Smoked Boston Butts & Lasagna. Good luck!