I think from a design point of view you need to keep a happy balance when you tackle the backgrounds, if you are going to use some really intense galactic backgrounds I'd advise to keep it a bit duller (darker and desaturated) than the source
examples of games using tonal and vibrancy control (darkening and desaturating, essentially dulling it into the background) they usually tend to keep one particular colour tone per background and some use screen filters to give the impression of the light from the galaxies reaching the players immediate surroundings, the first one is a graphic mod and is a tad on the intense side
this this thisand examples of games that have really intensely saturated galaxy backgrounds ( arguably not differing to far from reality)
this this this don't know about you but I find over saturated galaxies to look kinda cheap and eye hurtingly vibrant. another thing to add is that the games I have tried that have subdued galaxies have the benefit of being in 3D and some of them do have amazing and beautiful vibrant and vivid galaxy sections but they are strategically located in directions you barely ever look during gameplay even dog fights usually get fought on a relatively strict plane, so they never get in the way of gameplay.
I think you want it to be subtle to avoid the background grabbing equal or more attention to the foreground, even facet's example kinda draws your attention a bit more than you might want, just editing Facet's
here is to some degree how much I'd attempt to pacify it. because you need to keep the main focus and a consistent level of separation on your play field, and sometimes It's incredibly hard to focus on enemy ships when the background is taking up so much of your visual attention. your posted mockup was sufficient in that regard, but yeah if you wanted a more visually interesting BG that would be my advice
I like you're designs so far

and that latest space ship looks pretty baddass like the space ship equivalent of a Harley Davidson, so is it going to be strictly 1 player ship? upgrading and or getting new ships is always cool

and function wise the middle ship isn't too bad, in space there is no drag so stream lining them isn't an issue