This article by Joe St. Pierre on Bleeding Cool is pretty on point in my opinion. I've come to understand over my time publishing comics some of the do's and don'ts. If you have a freaking awesome cover that a huge artist makes for you just make it your cover and use the one you already have for something else. I'd also like to add that doing a Kickstarter you should limit the size options for shipping purposes. DON'T do any 11x17 Prints.