Hi James, I had this thought come over me a couple days ago thinking that you know where you can make maps wider or longer could there be an option to widen a map either west or east?
This would be something to raise in the Standard forums, since as far as I'm aware terrain generation in Extended is exactly the same as in Standard (which would be the hard part technically), and there is nothing specific to Extended about this feature request. (Perhaps James can move it there.)
Just rotate the map once or twice before extension should do the trick.