I'm not sure, myself, what I would have used for the cover. I like the one I got, and it's definitely a cover that gets people to look at it -- which is the primary point of the cover. OTOH, I'd hate to have the cover mislead people into thinking, oh, they're getting Jurassic Park VS the Space Force or something.
Here's an interesting question: if you (reading this) have read any of my books, what would YOU choose as a cover for those books? Would it be a scene from inside the book (and which one), would it be something more conceptual that captured what you saw as the "spirit" of the book (and what would that be), etc.?
[EDIT] I wish I was at liberty to show the concept sketches Kurt made for Boundary -- he did quite a few. And many of the suggestions made here are reflected in those concept sketches. He'd clearly read the book.
(I was actually surprised that Jim didn't select a scene involving Maddie, the Hot Blonde; there were a couple I think would have worked)