I have been doing them as the main cover being just the front cover (even at large size) and the wrap-around being an "alternate" cover. Strictly speaking, it's not truly an "alternate" cover, but as a matter of practicality, I find this advantageous. Because a wrap-around, at the same resolution of the front cover, would naturally be twice as big as the front cover, the only way to make a wrap-around large size fit the 100k limit is to reduce it to half size. This typically results in a loss of detail I personally find unacceptable. So it's better, I think, to give a very clear idea of what the front cover looks like, and then to give a smaller, more general idea of what the cover as a whole looks like.