You can use this idea as the Last resort:
There are plenty of Online galleries with military art, e.g.
Military Art. Find a picture with interesting plot and recreate it in the space enviroment with your own models starring.
Plagiarism? Sure.
Now add some objects to the scene, or remove something, change point of view (camera position) - make your scene different.
Plagiarism? No, artistic remaking
edit: fixed link