As it stands, the Zeph is at more than 50k tris and I'm not overly fond of going any further over that amount. I can always add detail using normal maps as well.
I would be willing to mess with the silhouette a little bit if I knew what you had in mind.
The 50k Tris come mainly from the Gas Tanks, which just proves that polycount =\= detail. You can solve the Gas Tank problem with detail boxes
The Zephyrus is one of those odd and complex cases, because the Gas Tanks are a very high frequency noise area, that covers about 40% of the ship's area, which makes designing an HTL version of it quite complicated.
I took a screengrab of your p3d, and did a quick paintover (sorry for the imperfect perspective, but I went for speed). Note that I barely touched the wee small details, and instead focused on the big shapes, structure definition. It should add more interest when you see the ship from far away, and I believe it balances out all that "noise" from the Gas Tanks.
If you end up changing your mesh, I'd say don't be afraid to be bold and exaggerate the shapes.
[attachment kidnapped by pirates]